Empiricism and rationalism are bound, in scientific thought, by a strange bond, as strong as that which unites pleasure and pain.

—Gaston Bachelard, The Philosophy of No

Introduction: The Philosophical Conjuncture

Speculative thinking is the soul of philosophy. But insofar as speculation is opposed to critique, it can only give rise to dogmatism. This has recently been made clear, once again, by the fortunes of “the speculative turn” in twenty-first century philosophy. Its most zealous promoters, converting the venerable legacy of speculative thought into the cultural capital of ersatz theoretical movements, have merely repeated the forms of dogmatism Kant and Marx rightly delimited while pretending to move beyond these critical delimitations.1 The lesson to be drawn from this waning episode of intellectual history is that although philosophy cannot allow critical reflection to cancel its speculative powers, speculation can only move forward in concert with critique. The claim of this book is that the mutually reinforcing relationship between speculation and critique, without which philosophy devolves into incoherence or common sense, depends upon sustaining the methodological tension between rationalism and empiricism.

One aim of Kantian critique was to displace the opposition between rationalist and empiricist orientations through the invention of transcendental philosophy. Delimiting pure reason and refuting the immediacy of experience, Kant’s philosophy aimed to ground any possible experience in transcendental conditions while invalidating the direct application of reason to knowledge of objects beyond possible experience. The competing claims of rationalist and empiricist thinkers to the priority of either reason or experience would be countered by the priority of the transcendental, which would ground the legitimate extension of both philosophical and scientific knowledge within critical limits.

In this sense, we could say it was the problem of ground that motivated Kant’s transcendental critique and that formed its horizon. Yet the figure of the transcendental subject could only be grounded by its own spontaneity, and this reflexive limit of cognitive conditions would pose an enduring problem for Kantian critique, since the unity of the subject (of the “I think”) could not itself become subject to critical interrogation. From a methodological perspective, we could say that the transcendental could only displace the opposition of rationalism and empiricism by ungrounding the subject of reason and experience whose knowledge it grounded. Or better: the transcendental deduction exposed, beyond its grounding of knowledge in conditions, the unconditional groundlessness of the subject of knowledge, which had already implicitly afflicted both rationalism and empiricism. Thus Heidegger could show that the internal structure of the transcendental schematism constitutes as temporal the very subject whose atemporal unity (the transcendental unity apperception) would delimit the ontological scope of reflection upon time by treating it as a form of intuition.2 Transcendental critique arrives at the limit of its critical vocation and pushes the speculative vocation of philosophy further not through the “failure” of critique but by ungrounding it, by undermining the very function of the subject as ground it had hoped to establish, and thus implicitly suggesting the methodological problem of (1) how critique can continue to function as ungrounded; and (2) how speculation is related to critique without grounds.

The answer to these questions, pursued and modeled in the following chapters, lies in a reengagement of the opposition between rationalism and empiricism—an effort to rethink the apparent contradiction between the priority of reason and the priority of experience without appeal to the priority of the transcendental, and thus in a manner shorn of transcendental guarantee.3 If we criticize the delimitation of knowledge to the field of possible experience—as we must—we thereby reopen the transcendentally displaced question of how the methodological relationship of rationalism and empiricism is to be theorized and practiced. If the transcendental does not suffice to ground the displacement of their opposition, because the subject of transcendental conditions is ungrounded, how can the claims of rationalism and empiricism be brought into a mutually reinforcing dialectic that does not accept or rely upon the priority of either method? I pose this question as the problem of the relationship between speculation and critique.

What I call rationalist empiricism involves the delimitation of transcendental philosophy through speculative critique. The methodological trajectory thus designated does not accept the severance of speculation from critique, nor critique from speculation. Rather, it aims to marshal the critical power of the tension between rationalism and empiricism to check one another’s claims and to propel those claims further. In order for this movement of critical delimitation and speculative extension to function, rationalism and empiricism can neither be collapsed into one another, nor defended as methodologically autonomous from or superior to the other’s claims. Nor can the tension of their opposition be displaced by appeal to transcendental grounds. Philosophy must sustain a relational disjunction of rationalism and empiricism in order to sustain the power of speculative critique.

By “rationalist” I mean to denote a philosophical orientation deploying the power of reason to push thought beyond the limits of experience, to explore what has to be thought according to the internal order and consistency of ideas. By empiricism I refer to a philosophical orientation claiming the genesis of ideas in experience and grounding the determination of what is the case on the consistency of thinking with experiential fact. But what are the limits of “experiential fact?” Is what happens in thought itself a form of experience? Does the exploration of the order and consistency of ideas itself yield experiential facts? Are there forms of experience that cannot be subordinated to knowledge gleaned from experience? What is at issue in such questions is how one determines criteria of the a priori and the a posteriori, and how exactly one conceives the relation of rationalism and empiricism to these categories. Rationalist empiricism denotes, one the one hand, a methodological attunement toward the experience of thinking as included in the field of what happens and, on the other hand, an attunement to the power of thought to push the field of facts beyond the presumed synthesis of the past with the future, referring what happens to what has to be thought, rather than to the succession of experience. I refer to “rationalist empiricism” rather than “empiricist rationalism” because it is the advent of reason, intervening in experience, that inaugurates philosophical speculation and that requires critique. Rational speculation cannot be grounded by or limited to experience, but it involves a commitment to empiricism insofar as it cannot violate the critical force of scientific knowledge. A rationalist orientation toward empiricism pushes beyond the limits of experience through the order and connection of ideas, but such an orientation can neither ground nor invalidate the criteria of experience within limits. The delicate task of rationalist empiricism is thus to preserve the distinction and autonomy of its methodological poles while also submitting each to the critical interrogation of the other, acknowledging and accounting for the discrepancy of their criteria.

This book limns a recessed history of rationalist empiricism in order to demonstrate the importance of this history to the methodological problems of contemporary philosophy. Through an engagement with these contemporary methodological problems, Rationalist Empiricism returns to the tradition from a perspective indifferent to the positioning of speculation against critique, or critique against speculation. What has been missed in debates concerning “the speculative turn,” I would argue, is a certain methodological complexity that often also goes overlooked in the work of Plato, Descartes, Hume, Hegel, or Marx: the refraction of rationalism and empiricism through one another’s criteria—sometimes in the form of methodological exceptions, sometimes in the systematic resonance of a concept absent from a system, sometimes through dialectical movement, sometimes through a non-dialectical encounter between thought and event. The methodological consequences of such refraction have to be reconstructed, have to be read back into the tradition from which they emerge, and my view is that certain texts of recent and contemporary French philosophy suggest the necessity of such reconstruction and offer a guide to its means.

One of these is Quentin Meillassoux’s After Finitude: An Essay on the Necessity of Contingency. The reception of Meillassoux’s slender tract has focused primarily upon its polemics, its examples, its concepts, and its proofs: the critique of correlationism, the figure of the arche-fossil, the concept of “hyper-chaos,” the proof of the necessity of contingency. What I find striking about the book is its method. By this I do not mean, as has often been emphasized, its style—the clarity of its argumentation and the classical tension between rhetorical concision and explosive conceptual development that it deploys. I mean that Meillassoux is both a rationalist and an empiricist, both a Cartesian and a Humean, and that he shows, perhaps for the first time, precisely how the philosophical itineraries of Descartes and Hume are not only compatible but carry one another toward singular ontological and epistemological consequences when reconstructed from a particular point of view. Obsessed with the relation between Descartes’s Meditations and Hume’s Enquiry as a student—with the theory of primary and secondary qualities, and with the problem of induction—I later recognized in Meillassoux’s book an engagement with questions I had often reflected on, though never formulated with such precision: If the articulation of Hume’s problem is not a specimen of philosophical skepticism, but rather a disavowed token of rationalist confidence, how does it comport with Descartes’s understanding of the distinction between the fragile evidence of sensory phenomena and the formal construction of primary qualities? What bearing does Descartes’s mathematical rationalism have upon the problem of causality articulated by Hume? And if we find Kant’s solution to such questions (transcendental critique) unsatisfactory, while also finding ourselves unable to settle into speculative assertions that would merely posit the absolute, how can we carry forward the strange and unresolved consequences of Hume’s argument while still holding onto the prospect of what Descartes theorized as knowledge of primary qualities, or what Spinoza would call “adequate ideas?” I could not have articulated these questions in this form before reading Meillassoux’s work, but they had nevertheless pressed upon me since I began to study philosophy. That is why I gravitated toward the issues at stake in After Finitude, despite what also struck me as an increasingly superficial reception of the book, foregrounding slogans and anti-critical polemics rather than more subtle dimensions of the methodologically complex way its arguments were made.

For me the real consequences of Meillassoux’s book lay in its repositioning of the apparent opposition between rationalism and empiricism, which Kant’s transcendental critique had not quite foreclosed. This repositioning revived not only the speculative vocation of philosophy but also the problem of the relationship between speculation and critique. This latter problem was made all the more pressing by the fact that, unlike some of his contemporaries, Meillassoux proceeded with deep respect for the philosophical questions opened, rather than obviated, by Kantian critique. Meillassoux affirmed that the question posed by “the problem of ancestrality”—“what is the condition that legitimates science’s ancestral statements?”—“seems to be a question of the transcendental type,” but he recognized its peculiarity, “in that its primary condition is the relinquishing of transcendentalism.” He criticized the reduction of knowledge to a subjective correlate imposed by “correlationism,” yet he demanded that “we remain as distant from naïve realism as from correlationist subtlety.” He understood that “the virtue of transcendentalism does not lie in rendering realism illusory, but in rendering it astonishing; i.e. apparently unthinkable, yet true, and hence eminently problematic.”4 The field of this problematic, rather than its summary dismissal by dogmatic fiat, would remain the field of his investigations, and the difficulty of the question accounts for the patience with which he has engaged his philosophical project, having now worked for decades on the problems opened by his doctoral dissertation rather than rushing toward the publication his philosophical system. To recognize that the virtue of transcendentalism lies in its precise formulation of the problem of speculative philosophy, though it did not solve it, necessitates a careful and mature disposition with respect to critique, rather than a simple rejection of its imperatives.

In my view, neither “the problem of ancestrality” nor Meillassoux’s anhypothetical argument for the necessity of contingency is the real core of After Fini tude.5 Rather, Meillassoux’s most consequential argument is his reactivation of the problem of induction through refutation of its foreclosure by probabilistic reasoning, a refutation drawing upon Alain Badiou’s ontological mobilization of Cantor’s transfinite detotalization of the infinite. Through the rationalist mobilization of mathematical formalism, Meillassoux reopens a central critique of both rationalism and empiricism: Hume’s demonstration that we have neither rational nor empirical grounds for assuming the constant conjunction of causes and effects, and thus we cannot assume the necessary stability of the laws of nature. Meillassoux resolves this critique in such a way as not only to support the absolute scope of philosophical rationality but also in a manner sustaining consistency with the capacity of the physical sciences to construct adequate knowledge of the properties of objects. Hume’s supposed “skepticism” concerning the constant conjunction of cause and effect was in fact a form of pragmatism; although we cannot affirm the necessity of causal regularities through either reason or experience, we can have confidence (through the synthesis of habit) in the probabilistic regularities of events. It is not Hume’s pragmatism but its covert metaphysical implications that Meillassoux displaces by questioning the application of probabilistic reasoning as a resolution of the problem of induction, and by recognizing Hume’s “skeptical doubts” as true knowledge of the contingency of physical laws and the nullity of the principle of sufficient reason. Deploying this nullity to support the claim of philosophical rationalism to think the in-itself (the necessity of contingency) in a manner consistent with the power of empirical science to establish non-correlational knowledge of objects, Meillassoux reasserts Hume’s central argument toward a revival of both rationalism and empiricism averse to the transcendental displacement of their opposition.


If After Finitude implicitly shows that the critique of the transcendental enables an unexpected alliance of rationalism and empiricism and a repositioning of their tension, rather than a repetition of their pre-critical opposition, its indications on this point hardly fell from the sky. In 1966 Louis Althusser delivered a lecture titled “The Philosophical Conjuncture and Marxist Research,” in which he used the term “rationalist empiricism” to name a tradition running, on the one hand, through the vulgar materialist ideology of “certain scientific practices (psycho-physiology, etc.),” and on the other hand from Descartes, to d’Alembert and Diderot, to Auguste Comte, and then through the work of Jean Cavaillès, Gaston Bachelard, Alexandre Koyré, and Georges Canguilhem.6 It is this second tradition of rationalist empiricism, Althusser claims, that “saved the honour of French philosophy” amid the “religious-spiritualist” reaction of the nineteenth century.7 Knox Peden’s outstanding work of intellectual history Spinoza Contra Phenomenology: French Rationalism from Cavaillès to Deleuze has shown how elements of this tradition functioned as a rationalist bulwark, steeped in Spinozism, against the dominance of phenomenology in twentieth-century French philosophy. For my part, I am interested in returning to the riddle of the compound term with which Althusser designates this tradition, and which he never explicitly followed up. How are we to understand the relation between rationalism and empiricism he alludes to but does not fully theorize, and what are its stakes for addressing the philosophical conflict between idealism and materialism? I try to solve this riddle in Chapter 2.

Althusser’s term “rationalist empiricism” alludes to a tradition of French thought focused on the epistemology of science, concerned in particular with how the empirical results of experimental scientific practice are constructed as scientific knowledge through the rational power of mathematical formalism. The apparent methodological paradox through which Althusser named this tradition would have been assimilated more readily among an audience intimately familiar with the epistemological writings of Gaston Bachelard, who declared in La philosophie du non (1940) that “rationalism and empiricism are bound, in scientific thought, by a strange bond, as strong as that which unites pleasure and pain.”8 In a passage that will be central to the present study, Bachelard argued that

the one triumphs by assenting to the other: empiricism needs to be understood; rationalism needs to be applied. An empiricism without clear, coordinated, deductive laws can be neither thought not taught; a rationalism without palpable proofs and without application to immediate reality cannot fully convince. The value of an empirical law is proved by making it the basis for a chain of reasoning. A chain of reasoning becomes legitimate by becoming the basis of an experiment. Science, the sum of proofs and experiments, the sum of rules and laws, the sum of evidences and facts, thus needs a philosophy with a double pole. To be more exact, it needs a dialectical development, since every notion is illuminated in complementary fashion from two different philosophical points of view.9

Because science involves a complementarity of empiricism and rationalism, through which “the one completes the other,” it requires a philosophy that can recognize and situate its dialectical development through an “epistemological polarity,” such that “to think scientifically is to place oneself in the epistemological field intermediate between theory and practice, between mathematics and experiment.”10

Thus, it is not only science that depends upon the mutually critical and constructive relationship between rationalism and empiricism; the relationship between science and philosophy also depends upon such a dialectic. It is only through such a dialectic that the “epistemological obstacles” theorized by Bachelard can be overcome.11 “Only too often,” he writes,

the philosophy of science remains corralled in the two extremes of knowledge: in the study by philosophers of principles which are too general and in the study by scientists of results which are too particular. It exhausts itself against these two epistemological obstacles which restrict all thought: the general and the immediate. It stresses first the a priori and then the a posteriori, misrecognizing the transmutation of epistemological values which contemporary scientific thought ceaselessly executes between the a priori and the a posteriori, between experimental values and rational values.12

Note that this “transmutation of epistemological values” has two conditions, one explicit and one implicit. Explicitly, it requires that rationalism and empiricism not be “corralled” as separate methodologies, each unable or unwilling to recognize the consequences of the other for its own practices and its own results. But implicitly, it also requires that rationalism and empiricism be held sufficiently apart that their distinct epistemological values can “transmute” one another. What is called for is not a synthesis or a displacement of the opposition between rationalism and empiricism that would go by some other name (for example, the transcendental). Rather, what is called for is a relational disjunction between methodological orientations with discrepant epistemological values. The transmutation of these values operated by scientific thought occurs “ceaselessly”—not once and for all. It is in this sense that the mutually critical force of rationalism and empiricism, as they encounter one another’s imperatives, is without grounds: it relies upon an absent place between methodological values, across which they can pass, within which they can interfere, through which they can complicate, refute, or propel one another. Reason and experience can say “no” to one another because they have not been synthesized; they can integrate each other because they are not indifferent to the other’s claims.

Though they formulate the conditions for a methodological critique of the transcendental, perhaps Bachelard’s claims will not seem particularly revelatory with respect to the epistemology of science. Yes, of course, science relies upon the empirical testing of mathematically formulated theories, and it relies upon the mathematical formalization of experimental results. But the philosophical consequences of Bachelard’s methodological dialectic are more curious. For example, following his remarks about the epistemological polarity of rationalism and empiricism, and about the epistemological field mediating between theory and practice, mathematics and experience, he tells us that “to know a natural law scientifically is to know it at once as phenomenon and as noumenon.”13 What is interesting here is that Bachelard retains the distribution of Kant’s categories—wherein phenomena are objects of experience while noumena can only be thought by reason—while rejecting the firm epistemological divide Kant had imposed between them. Natural laws, for Kant, are laws of phenomena, which can in no way be known as noumena themselves, nor applied to knowledge of noumena. Yet Bachelard claims that the methodological dialectic of scientific thought gives us knowledge, “at once” (à la fois), of the same thing (a natural law) as both phenomenon and noumenon. How can we make sense of this thesis?

What is at issue here is the status of knowledge per se. What is it to know something? In particular, how does the constitution of knowledge bear upon the distinction between objects of experience and objects of reason? To know a natural law, according to Bachelard, is to know it as both of these at once. In my view, it is the ground of knowledge that is at stake in such a claim. According to Kant, objects of experience can be known because they are grounded by transcendental conditions that determine their presentation as phenomena, as part of “nature” considered as the realm of transcendental laws. Objects of reason cannot be known precisely because they are not grounded by categorial conditions; the categories of the understanding cannot properly be applied to them, and thus they can only be thought. The distribution of objects between experience and reason (phenomena and noumena) and the distribution of mental activity between knowing and thinking are thus correlated to a distinction between the grounded and the ungrounded. According to transcendental philosophy, only that which can be grounded can be known. Bachelard’s epistemology of science depends upon surrendering this distinction: upon a radical acceptance that knowledge is without ground. To surrender the transcendental is to surrender the grounding of knowledge by transcendental conditions; the ground of the transcendental is replaced by the ungrounded dialectic of rationalism and empiricism.

This dialectic is ungrounded because it relies upon an alternation between epistemological poles that do not share criteria, yet which counter and inform one another through a transmutation of epistemological values across differential criteria. Because this transmutation is “ceaseless,” it never settles upon a ground; its epistemology is genetic, in the sense that what Bachelard calls the “rectification” of knowledge is continuous and recursively transformative. What we know undergoes revision through the differential imbrication of reason and experience, their exposure to one another’s discrepantly constituted fields of coherence, entailment, and legibility. What is at issue in such an epistemology is not so much a distribution of faculties within a subject of knowledge as the distribution of methodological coherence across a historical process open to the perpetual reconstitution of what can only seem to be its grounds. This is why Bachelard says that “the philosophy of physics is perhaps the only philosophy which is applicable even when it decides to overstep its own principles. In short it is the only open-ended philosophy. All other philosophies posit their principles as intangible, their primary truths as total and complete.”14 Scientific thought has to be able to overstep its principles because its principles must remain subject to correction by future developments, and such openness is itself the principle of a method ungrounded by either reason or experience but rather constituted by the perpetual transmutation of their values.

How can knowledge of noumena be subject to correction? Or, to put the question the other way around, how can revisable knowledge be knowledge of noumena? This is the epistemological problem with which Bachelard’s formulation confronts us, and we can approach it through the problem of ground if we begin not with noumena but with phenomena. If it is the basis of transcendental grounding that distinguishes objects of experience from objects of reason, and thus knowledge from thinking, then this distinction does not hold; so far as modern science is concerned, objects of experience are not grounded by the transcendental conditions of a cognizing subject. On the contrary, they are accessed through scientific apparatuses, by the technological constitution of givenness, not by that of transcendental categories. And even this technological constitution of givenness itself is not necessarily relayed to or by subjects through the synthesis of intuitions and concepts; scientifically, it is made legible through mathematical formalizations, into whose orders of coherence it is translated. Of course, the categorial structure of cognition is relevant to the interpretation of results (e.g., what sort of causality is at issue in the double-slit experiment of quantum mechanics). But the integration of technological givenness into mathematical formulae, their chains of entailment and their recursive modification, are indifferent to competing interpretations of the formalisms, and they need not obey the formal regularities by which objects of human perception are constituted. This discrepancy between scientific results and perceptual regularities is the source of modern science’s formidable evasions of the synthesis of receptive intuition with the categories of the understanding.

Technological conditions for the constitution of givenness are not transcendentally grounded insofar as they are themselves historically transformed and transformative. There is a historical technogenesis of “experience” itself, of the conditions of all possible experience, insofar as the field of what becomes technologically available to experimental inquiry undergoes ceaseless alteration, and it does so in concert with transformations of scientific knowledge. We could say that the availability of phenomena to experience is grounded in technological capacities, but the historical transformation of these capacities is itself ungrounded. It is itself subject to the dialectic of reason and experience, experiment and formalization, which generates transformations of scientific knowledge and concretizes the latter in devices, apparatuses, mathematically configured and accountable experimental setups. Since the reconstitution of technological capacities is a historical process that is itself constantly involved in the transmutation of epistemological values theorized by Bachelard, its condition of possibility is precisely that it be shorn of transcendental guarantee. What Kant said of noumena—that knowledge of noumena cannot be grounded, and thus is not knowledge—can be both accepted and transformed with respect to experimental phenomena: the technological conditions by which phenomena are constituted are ungrounded, and scientific knowledge changes on this condition. Since knowledge of phenomena is not only knowledge of what can be observed through regularities of perception but also observation and formalization of what cannot be made accessible through regularities of perception, to know a natural law scientifically is to know it at once as phenomenon and noumenon. The condition of possibility of this “at once” is the surrendering of transcendental ground as the fundamental criterion of knowledge, and the opening of knowledge to the ungroundedness of its historical transformation. This historical transformation works through the non-synthetic, relational disjunction of rationalism and empiricism, mathematics and experiment, formalization and technogenesis.

To know something as both phenomenon and noumenon is to know it as both empirically and rationally constructed, as neither given nor refractory to determination. A natural law is known as phenomenon insofar as it is determined, as least partly, through experimental observation. It is known as noumenon insofar as it is inaccessible to experimental observation. It must be determined as an object of reason, but this determination is also mediated by the experimental constitution of objects of experience. The rationally determined setup of the experiment, the multiplication of modes of technical perception, the filtration of indexical traces through formalization, the routing of mathematical formalizations back through new technological concretions, and so on—these produce and “stratify” regularities of experimental perception in such a way that they cannot simply be understood as given. Such stratification constructs an object of knowledge that is neither given to experience nor separated from its determinations: an object of reason that is not purely thought, but rather constrained by experimental protocols and extrapolated by rational methods. We know something at once as both phenomena and noumena insofar as we know it both through observation and as it could never be observed. We know it in a manner that could never come under the transcendentally constituting conditions of a subject, but rather through the ceaselessly reconstituted conditions of an ungrounded historical process without a subject. That is: a process in which subjective determinations are displaced, refracted, dispersed, and reconstituted in a complex of determinations traversing technical, mathematical, and experimental protocols exceeding the synthesis of subjective faculties.

Bachelard transforms Kant’s categories. By phenomenon Bachelard means: constituted by conditions of experimental observation (object of experience). By noumenon he means: formally determined by rational, mathematical extrapolation beyond conditions of possible experience (object of reason). Knowledge of the object of experience and the object of reason co-constitute one another, constrain and recursively refine one another, such that they become the same object (at once phenomenon and noumenon). But by knowledge of “noumenon” he does not mean absolute, direct knowledge of the thing-in-itself. Bachelard opens an epistemological field in which objects are known as both phenomenon and noumenon insofar as they are constituted as neither “for-us” nor “in-themselves.” This specifies the terrain of what I would call provisional objectivity. Scientific knowledge is “objective” for the same reason it is “provisional”: because it is constrained and enabled by fields of relational formalization and recursively refined experimentation, it is adequate to refutation and correction, and the process of its rectification is unlimited. That process defies subjective synthesis. Properties of an object are known scientifically insofar as it is constructed as an object of knowledge, but if this construction distinguishes the object of knowledge from the thing “in-itself,” it also distinguishes it from knowledge of the thing as it is “for-us.” Science renders objects of knowledge irreducible to either the in-itself or the for-us. Provisional objectivity suspends objects in the medium of construc tion, in a process of rational/empirical constitution that filters the givenness of subjective determination. It would be quite reductive to call this process “intersubjective,” since its transmission, assimilation, and recomposition depends not only upon relations between individual subjects but also upon technical apparatuses, inscriptions, necessary entailments of formal chains—upon the relaying of information irreducible to human observation, human thought, and human communication.15


Although Althusser deploys the term “rationalist empiricism” to characterize an epistemological tradition to which Bachelard was central, he does not often characterize his own epistemology in such terms. But we can read the dialectical transmutation of rationalist and empiricist epistemological values back into Althusser’s theory of science. Althusser’s distinction between “science” and “ideology” is more frequently dismissed than defended, but he makes clear in his “Lecture Course for Scientists” (1967) that there is no clean separation between the two.16 Rather, science requires a historical process of critique and clarification that perpetually intervenes in their relationship. Since science is always infiltrated by ideology, it requires forms of theoretical practice capable of subjecting ideology to critical interrogation. The criterion of “science” is the constitution of forms of knowledge capable of overcoming what Gaston Bachelard called “epistemological obstacles”—ideological impediments to such critique and clarification. A science is a form of knowledge that has arrived at mutually determining concepts and methods making possible a field of recursive, historical self-interrogation. The criteria of scientific knowledge are never fixed and can never be divorced from a practice in process; they are relative to the capacity of a conceptual and methodological field to subject itself to refutation, refinement, and generative conflict, which remains a ceaseless task. For Althusser, Marx’s critique of political economy founds a science because it elaborates a conceptual structure making systematically legible the ideological afflictions of a field of knowledge, thereby rendering its own elaboration open to a history of critique wherein the stakes of theoretical determinations and their application in practice can be recursively interrogated.

In “On the Materialist Dialectic,” Althusser schematizes the process of recursive self-critique by which science is constituted and sustained through his theory of the three “Generalities” (see Figure 1). By the term “generality” Althusser means to stress that:


Figure 1. Althusser’s Three Generalities. Generality II (present scientific theory) works [1] on Generality I (ideological or outdated scientific concepts) in order to generate [2] Generality III (knowledge: new concepts and conceptual relations). Generality III is integrated [3] into Generality II through revision of scientific theory, the production of new experimental apparatuses, the construction of new theoretical problems. Past elements of Generality II requiring revision in relation to present scientific theory become [4] elements of Generality I.

science never works on an existence whose essence is pure immediacy and singularity (“sensations” or “individuals”). It always works on something “general,” even if this has the form of a “fact”…. It does not “work” on a purely objective “given,” that of pure and absolute “facts.” On the contrary, its particular labour consists of elaborating its own scientific facts through a critique of the ideological “facts” elaborated by an earlier ideological theoretical practice. To elaborate its own specific “facts” is simultaneously to elaborate its own “theory,” since a scientific fact—and not the self-styled pure phenomenon—can only be identified in the field of a theoretical practice.17

These remarks offer a critique of vulgar empiricism—one that takes the objects of scientific practice to be pure phenomena that have not undergone a process of either ideological or theoretical transformation. Althusser emphasizes that science is continually involved with the discrepancy between theory, as constituted at present, and “facts” promulgated by ideological practices or devolving from earlier stages of science. The “raw material” upon which science works—which he names Generality I—is thus not pure phenomena but rather “ideological concepts” or “scientifically elaborated concepts which belong nevertheless to an earlier phase of science (an ex-Generality III).”18 Generality III denotes knowledge produced by such theoretical labor upon Generality I: new scientific concepts and conceptual relations. Generality II, which works upon Generality I to produce Generality III, is “the corpus of concepts whose more or less contradictory unity constitutes the ‘theory’ of the science at the (historical) moment under consideration, the ‘theory’ that defines the field in which all the problems of the science must necessarily be posed.”19 Note that the present state of scientific theory constitutes for Althusser both a field of knowledge and a field of problems: a problematic field through which new questions can be posed to old facts in order to generate new knowledge.20

Importantly, Althusser stresses that “scientific theory” (Generality II) “rarely exists in a science in the reflected form of a unified theoretical system.” Rather, it “includes the whole field of technique, in which the theoretical concepts are in large part invested” and “the explicitly theoretical part proper is very rarely unified in a non-contradictory form.”21 The present state of scientific “theory” is in fact a “theoretico-technical” complex capable of “pos[ing] an existing difficulty in the form of a problem.” We can thus locate in Althusser’s epistemological schema an uneven, complex, non-unified field of rational knowledge, experimental techniques, and technological apparatuses that works upon ossified “facts,” and we can say that what characterizes these ideological or outdated “facts” is that they have either become abstracted from or have yet to enter into the dialectic process of epistemological transmutation between reason and experience theorized by Bachelard. They must be addressed within the “theoretico-technical” field through which the present state of scientific theory (in all its tension between discrepant findings, regional theories, competing interpretations) works upon both pre-scientific intuitions and ossified formalisms, theories, or data to produce new concepts and empirical findings. The integration of this knowledge into scientific theory will then depend upon the capacity to coordinate rational and empirical values: the testing of speculative theory against experimental outcomes, the consideration of experimental outcomes within the framework of existing formalisms, or the transformation of those formalisms to accommodate empirical findings.

From a philosophical perspective, which he gleans from Marx’s methodological considerations in the introduction to the Grundrisse, Althusser stipulates that the ideological opposition between the abstract (theory) and the concrete (reality) should be displaced by a relation between two concretes: “the concrete-in-thought, which is a knowledge, and the concrete-reality which is its object.”22 (See Figure 2.) It is not that the rational is abstract and the empirical concrete. What is merely given is abstract and must undergo a process of elaboration to transform it into concrete knowledge. What has to be theorized is not an opposition between the empirical (supposedly concrete) and the theoretical (supposedly abstract), but rather the transformation of ossified facts into the concrete-in-thought (Generality III) which has the concrete-real as its object of knowledge (we will return to this point shortly). Marx describes the transformation of the abstract into the Gedankenkonkretum as “the working-up of observation and conception into concepts” (der Verarbeitung von Anschau ung und Vorstellung in Begriffe).23 Thus, concepts are produced through the dual elaboration of both what is observed (Anschauung) and what is conceived (Vorstellung). The merely given becomes concrete through the integration of observations into conceptual schema and the encounter of rational determinations with empirical facts, their mutual Verarbeitung. In order not to become ideological—not to languish in received ideas or self-evident truisms—knowledge must be continually expelled by and reintegrated into the dialectic of the rational and the empirical, transformed within an operative, never fully unified or totalized theoretico-technical complex.


Figure 2. Abstract, Concrete-in-Thought, Concrete-Real. Althusser displaces the association of theoretical knowledge with the abstract, as opposed to the concrete. What is abstract is inadequate knowledge (ideology, ossified fact, the self-evidence of pure phenomena), while theoretical knowledge is the “concrete-in-thought” (a term borrowed from Marx).

Within the framework of the physical sciences, the recent project to redefine the kilogram unit offers a striking example of this methodological dialectic in action (I treat this example in detail in Chapter 6). The gram was initially defined, in 1795, as the mass of one cubic centimeter of water at the melting point of ice (thus, a kilogram has the mass of one cubic decimeter of water). This definition relies in turn upon the meter unit, which was defined in 1791 as one ten-millionth of the length of a quadrant along the Earth’s meridian through Paris. These quantities were established experimentally—in the case of the meter, through the famous surveying project carried out by Delambre and Méchain from 1792 to 1799.24 Platinum reference objects instantiating the length of the meter and the mass of the kilogram were then fabricated and deposited in a vault in Sèvres. When the metric system was adopted internationally in 1889, new reference objects were fabricated, and definitions of the meter and the kilogram were tied directly to these: the meter was defined as the length of the prototype meter bar; the kilogram as the mass of the kilogramme des archives. The meter has since undergone several redefinitions, most recently as the length of the path traveled by light in a vacuum during a time interval of 1/299,792,458 of a second. In November 2018, the kilogram was redefined in terms of the Planck constant.25 This means that the physical object which previously instantiated the kilogram unit no longer grounds its definition, just as the meter bar was previously eclipsed by reference to a physical constant (c, the speed of light).

The meter bar and the kilogram prototype are concretizations of theoretical knowledge: they instantiated the rational coordination of empirical findings in standards of reference for the ongoing quantitative determinations of scientific practice. Yet the kilogram prototype has been replaced because it had become abstract. No matter how carefully it is preserved, the object gradually accretes irregularities altering its mass, but because its mass is by definition 1 kg, these cannot be accounted for in an operative stipulation of how much its mass has drifted. Redefinition of the kilogram in terms of the Planck constant establishes a fixed quantity (a quantitative determination of the physical constant h), and this required an internationally coordinated effort to measure the Planck value itself with reference to the kilogram as previously defined, through equations correlating electricity to mass. Since 2014, through two fundamentally different experiments, the quantity h has been measured below a particular threshold of uncertainty. The fixing of the Planck number means that this uncertainty migrates to the kilogram unit itself (a far lesser degree of uncertainty than that previously attending the definition of the unit). “The kilogram” (object and unit) thus undergoes what we might think of as a process of reconcretization with respect to scientific knowledge: it is incorporated into a new system of theoretical knowledge coordinated with our best existing technologies, experimental procedures, and formalizations, such that the frame of reference previously grounding the unit is not only displaced but integrated into a new referential context. Meanwhile, what the Planck number designates—the minimal quantum of physical action—is that which is measured in the experimental campaign to redefine the kilogram; it is the concrete-real to which these measurements refer. It cannot be measured with exact accuracy, but it can be measured by experiments with determinate uncertainty and quantified within a margin of 20 parts per billion (2.0 × 10-9). The “real object” (quantum of action) remains exterior to its theoretical determination (it is what is determined by theory). But it has also become a rigorously specifiable object of knowledge, known with a determinate degree of uncertainty within an experimental and theoretical system of reference. The history of measurement recursively refines the very units (kg) upon which it is predicated; it does so through the measurements it makes available (h); and it does so through the integration of measured quantities into interrelated formalizations, such as those relating energy to both the Plank number and to mass (e.g., E = hv; E = mc2), coordinating empirical evidence with rational logic and enabling new programs of theoretico-technical research.


Having begun to articulate an approach to rationalist empiricism by drawing together Bachelard’s and Althusser’s theories of scientific knowledge, we can now address some of the problems with the relatively thin realist epistemology put forward by Meillassoux in After Finitude. First of all, how can we square Meillassoux’s defense of the Cartesian distinction between primary and secondary qualities with the “non-Cartesian epistemology” formulated by Bachelard?26

We should bear in mind Bachelard’s stipulation that his “non-Cartesian philosophy complements Cartesian philosophy without contradicting it.”27 What he objects to in Cartesian epistemology is its fundamentally analytical method: the grounding of knowledge upon simple ideas according to the principle that “no construction is clear to the mind unless the mind knows how to take it apart.” According to Bachelard, “Descartes never pays heed to the reality of the complex, to the emergence of qualities in the whole not evident in the parts,” whereas “modern science begins with synthesis.”28 Epistemologically, he argues, modern science “relies for clarity on combining ideas rather than on trying to understand individual objects in isolation. In other words, instead of intrinsic clarity it relies on what I shall call operational clarity. Relations do not exemplify objects; objects exemplify relations.”29 Bachelard thus proposes a relational realism according to which

there are no simple phenomena; every phenomenon is a fabric of relations. There is no such thing as a simple nature, a simple substance; a substance is a web of attributes. And there is no such thing as a simple idea, for … no idea can be understood until it has been incorporated into a complex system of thoughts and experiences.30

These formulations emphasize once again that the relational epistemology of “modern science” cannot be grounded by either rationalism or empiricism in isolation; it depends upon the transmutation of experience and reason, a “complex system of thoughts and experiences.”

Such a relational epistemology renders the philosophical expression “in itself” equivocal, insofar as it is meant to refer to the thing in-itself. On the one hand, the expression designates the independence of the thing from human perception or knowledge, the separability of the object of our knowledge (concrete-real) from our knowledge of the object (the concrete-in-thought). On the other hand, it implies the independence of the thing per se, the separability of objects from relations. In this sense, the “thing in-itself” would designate the simple nature, or simple substance, whose existence Bachelard rejects (on the grounds that it is incompatible with physical theory). It is this second possible sense of the term from which Meillassoux’s terminology in After Finitude needs to be disentangled, while retaining his emphasis on the first. We can reconstruct Meillassoux’s “Cartesian thesis”—“all those aspects of the object that can be formulated in mathematical terms can be meaningfully conceived as properties of the object in itself”31—in such a way that it retains its Althusserian sense (the concrete-in-thought refers to and establishes knowledge of a concrete-real that “survives in its independence, after as before, outside of thought”) without requiring absolute knowledge of simple natures. That is, we can show that Bachelard’s non-Cartesian epistemology complements Meillassoux’s Cartesian thesis without contradicting it—and we can do so by thinking through the inclusion of that Cartesian thesis within the larger framework of rationalist empiricism.

Consider the object of scientific investigation with which Meillassoux is most directly concerned in the first chapter of After Finitude: the earth. The accretion of the earth is an “ancestral” event insofar as its existence pre-dates the emergence of the human species and terrestrial life. From a Cartesian perspective, it is also an event anterior to the existence of those secondary qualities that are specifically modes of relation between a living creature and its environment (e.g. color, heat, scent), such that an ancestral event is only meaningfully described through reference to primary qualities (e.g., wavelength, temperature, chemical reactions).32 Rather than specifically perceptual information, Meillassoux stipulates,

all that can be formulated about such an event is what the “measurements,” that is to say, the mathematical data, allow us to determine: for instance, that it began roughly 4.56 billion years ago, that it did not occur in a single instant but took place over millions of years—more precisely, tens of millions of years—that it occupied a certain volume in space, a volume which varied through time, etc.33

These mathematical data are derived from measurements contemporaneous with us and made available within a particular framework of scientific theory,34 but they specify information about a referent (the accretion of the earth) that preceded our very existence and thus did not itself exist as the correlate of our experimental protocols.

Did not itself exist: What is the “itself” that is referred to here? It is the independence of the physical process under scientific investigation (the accretion of the earth) from our knowledge of that process, the independence of the concrete-real about which we know through the concrete-in-thought. It thus pertains to the “in-itself” in the first sense of the term elaborated earlier: we know that the object of our knowledge is separable from our knowledge of the object. But is it an object that we know about? The earth is an object (a planet), but the accretion of the earth is a process, and studying it offers an excellent object lesson in the processual, relational constitution of “things in-themselves.” We are studying the temporal constitution of the object, its formation as an object, which implies that the alterations it undergoes to become the object it “is” do not simply cease once it has formed—as if there were a specific instant at which its form were established once and for all.35 Mathematizable properties of the object (the datable duration of its formation) make clear that it is not a simple substance or a simple nature, that it is not a “thing in-itself” in the sense that it is thinkable as discrete and self-identical. The thing that the earth is exists as a process that reaches a certain threshold of stability, but that also never freezes into unchanging self-identity. This is true of all objects.

Part of what is at issue here is the passage of a property Kant understood as relevant only to objects of experience (temporal constitution) over to the designation of things in-themselves—which from the perspective of Kantian philosophy could not be subject to transcendental time determinations. This terminological difficulty drives home that the provenance of the term “thing in-itself” (Ding an sich) is Kantian rather than Cartesian. In a sense, this is exactly Meillassoux’s point: the correlational reversal of our thinking about the relation between time and objects is so profoundly embedded in the frameworks of Kantian, Hegelian, and Heideggerian philosophy that our philosophical terminology is “itself” difficult to disentangle from their conceptual schemata. In this respect, however, Meillassoux’s references to the “thing in-itself,” or properties of “objects in-themselves,” are sometimes conceptually equivocal and rhetorically infelicitous. While rejecting Kant’s proscription upon knowledge of the in-itself, Meillassoux does want to retain a Kantian distinction between the “in-itself” and the “for-us” so as to block the post-Kantian collapse of that distinction in German idealism from Fichte through Hegel. But in doing so, he draws the Cartesian distinction between primary and secondary qualities into a sometimes uncomfortable relation to a Kantian terminology difficult to disentangle from the conceptual distributions of transcendental critique.

Meillassoux’s Cartesian thesis is that “all those aspects of the object that can be formulated in mathematical terms can be meaningfully conceived as properties of the object in-itself.” But it is precisely the specifiable uncertainty of quantities determined by measurement that gives the quantitative determination of properties scientific meaning.36 A measurement of the length of my desk (189.2 cm) has scientific value only if I can determine and stipulate the uncertainty of my measurement, which would require a more complex experimental apparatus than my tape measure. Meillassoux acknowledges (of course) that a measurement can be supplanted by one that “exhibits greater empirical accuracy” and that “empirical science is by right revisable.”37 His claim is that the referent of revisable determinations is external to the determinations themselves, and that these determinations constitute revisable knowledge of those referents: “science does not experiment with a view to validating the universality of its experiments; it carries out repeatable experiments with a view to external referents which endow these experiments with meaning.”38 One might ask, however: If it is the specifiable uncertainty of a measurement that makes it scientifically valid, and if the quantitative determination of all measurable properties is attended by uncertainty, can an aspect of the object designated by an uncertain quantity be conceived as a “property of the object in-itself?” After all, it is not the property (or the aspect of the object) that is uncertain “in-itself;” it is the quantity designating it.

What do we know about objects or events, through our quantitative knowledge, that is separable from the uncertainty of our quantitative knowledge? Thanks to radioactive dating techniques, we know that the accretion of the earth occurred billions of years prior to the genesis of the human species (and we did not always know this), though our knowledge of the age of the earth is attended by an uncertainty of some fifty million years.39 I could not quantify, exactly, the length of my desk, and measured at certain scales its length would not be a perfectly stable property. But I know that its length is greater than that of the keyboard it supports. Such examples might seem trivial, but they exemplify an interesting fact: although I cannot assign a perfectly accurate quantitative value to a property of the object “in-itself,” I can know something else about the object, which can be abstracted from my relation to it, on the basis of a determinately uncertain quantitative value that I assign to a metrological model of the object (i.e., the object as determined by measurement).40 What poses a problem for the exact assignment of quantities to objects in-themselves (determinate uncertainty) does not necessarily pose a problem for knowledge of quantitative relations among objects. If I know that the uncertainty of a measurement is within a certain margin, then I can also know something about the relative properties of different objects that is not compromised by that margin of uncertainty (e.g., my watch has more mass than my ring). Thus Bachelard refers to “the realism of algebra.”41 Mathematical formulations of physical laws formalize relations among quantitative properties that have been, or will be, determined with particular degrees of uncertainty.

This is part of what Bachelard means when he claims that “simple ideas are not the ultimate basis of knowledge; after a complete theory is available, it will be apparent that simple ideas are in fact simplifications of more complex truths.”42 The number designating the speed of light in a vacuum (c) has now been fixed exactly, but the uncertainty of its determination has shifted to the unit in which it is expressed (m/s). The scientific meaning of the value depends on this complex sense. The earth, considered as an “object in-itself,” does not have an exact age that is a quantifiable property, since the exact moment of its origin is logically impossible to specify. That is implicit in its existence as a physical, rather than logical, entity. But our knowledge of the relation between well-established quantitative ranges within which the accretion of the earth, the origin of life on earth, and the origin of humankind took place enables relational determinations and logical extrapolations from empirical measurements that are consequential. Moreover, we can say that these are true, and that the knowledge we glean from them about the relative chronology of events refers to events exterior to knowledge. Meillassoux is interested in our scientific knowledge of a physical order of time that is not subsumed by phenomenological time, that is separable from phenomenological time, and that can be known logically on the basis of empirically determined quantities:

Science reveals a time that not only does not need conscious time but that allows the latter to arise at a determinate point in its own flux. To think science is to think the status of a becoming which cannot be correlational because the correlate is in it, rather than it being in the correlate. So the challenge is therefore the following: to understand how science can think a world wherein spatio-temporal givenness itself came into being within a time and a space which preceded every variety of givenness.43

If the empirically determined quantities that enable such thinking can be specified only with respect to metrological models of the processes concerned, knowledge of these models nevertheless enables logical inferences concerning physical, temporal relationships that are separate from the models. That is why the term “provisional objectivity” is appropriate to such knowledge.


Reference to the “in-itself” in After Finitude is complicated by another difficulty: that the term is used both to denote empirical, scientific knowledge of mind-independent objects or events and to denote speculative, ontological knowledge of being-qua-being. Here we must move beyond the epistemology of science to the question of how the speculative is related to the empirical in an ontological register. If Kant infringed upon the critical limits he had established by (1) assuming that the thing in-itself existed and (2) assuming that it was non-contradictory, Meillassoux asserts, “by way of contrast,” “non-metaphysical speculation proceeds in the first instance by stating that the in-itself is nothing other than the facticity of the transcendental forms of representation. Then, in the second instance, it goes on to deduce from the absoluteness of this facticity those properties of the in-itself which Kant for his part took to be self-evident.”44 Here “properties of the in-itself” refers not to empirically determinable quantities assignable to properties of objects, but rather to that which is not an object: to the necessity of contingency and to the law of non-contradiction. The ontological scope of speculative rationality goes beyond the empirically determinable properties of objects (beings) to determine absolute properties of being-qua-being. Meillassoux formulates the tension between reason and experience involved in such speculative rationality most clearly in his dissertation:

The canonical paradox of rationality is thus given in this form: reason presents itself as universal discursivity, necessary and true, thus as the thought of that which is—but that which is is given as particular and contingent. If reason is not a chimera, then it must resolve this problem: how to disengage, at the heart of the factual beings given in experience, that which, adequate to those beings, is not itself contingent?45

As I argue in Chapter 4, Meillassoux here reformulates the problem of the on-tological difference: whereas beings are contingent, the being of beings is the necessity of their contingency, and this is not itself a being (i.e., there is no necessary being; what is necessary is that all beings are contingent). Note that Meillassoux commits himself, in a manner I will later explore in detail, to drawing the rationalfrom the empirical: the problem is “how to disengage, at the heart of the factual beings given in experience,” that which reason can stipulate concerning what is not given in experience.

What interests me here is the mutually delimiting purview of the rational and the empirical implicit in the relation between Meillassoux’s speculative and epistemological argumentation. All that we observe is the contingency of beings and the regularity of physical laws, yet we can rationally affirm the necessity of that contingency: its absolute rather than factical scope, its insubordination to any law, and thus the ultimate contingency of the regularity of physical law itself.46 The empirical delimits the field of the rational, insofar as absolute contingency is not empirically manifest (but neither is it contradictory to what is empirically manifest); the rational delimits the field of the empirical, insofar as we can know that the regularity of manifestation does not delegitimate the absolute scope of the contingency of being. Absolute contingency is not ontically accessible; empirical contingency does not yield ontological truth. Science and philosophy limn different regimes of knowledge of the “in-itself,” insofar as we take this term to denote that which is independent of our capacity to determine its properties. Thus, on the one hand, we have to think the complicity of reason and experience, rationalism and empiricism, in the establishment of scientific knowledge. On the other hand, we have to distinguish the scope of that complicity from the power of speculative rationality to go beyond the field of scientific knowledge, without thereby invalidating the knowledge that science makes possible.

In Chapter 2, I argue that Meillassoux’s speculative ontology is consistent with his scientific epistemology and that the complexity of their consistency obeys and is indeed required by materialist criteria. Here I want to note that the speculative scope of Meillassoux’s argumentation has an important critical function, insofar as it delimits the concealed dogmatism of Kant’s transcendental theory of reflective judgment. Of course, reflective judgment is supposed to be that which, within the framework of transcendental critique, cannot be dogmatic, since it “attributes nothing at all to the object.” But consider the following passage from the Critique of the Power of Judgment, which I must quote at length given its centrality as a counterpoint to our theory of speculative critique:

we must think of there being in nature, with regard to its merely empirical laws, a possibility of infinitely manifold empirical laws, which as far as our insight goes are nevertheless contingent (cannot be cognized a priori); and with regard to them we judge the unity of nature in accordance with empirical laws and the possibility of the unity of experience (as a system in accordance with empirical laws) as contingent. But since such a unity must still necessarily be presupposed and assumed, for otherwise no thoroughgoing interconnection of empirical cognitions into a whole of experience would take place, because the universal laws of nature yield such an interconnection among things with respect to their genera, as things of nature in general, but not specifically, as such and such particular beings in nature, the power of judgment must thus assume it as an a priori principle for its own use that what is contingent for human insight in the particular (empirical) laws of nature nevertheless contains a lawful unity, not fathomable by us but still thinkable, in the combination of its manifold into one experience possible in itself. Consequently, since the lawful unity in a combination that we cognize in accordance with a necessary aim (a need) of the understanding but yet at the same time as contingent in itself is represented as the purposiveness of the objects (in this case, of nature), thus the power of judgment, which with regard to things under possible (still to be discovered) empirical laws is merely reflecting, must think of nature with regard to the latter in accordance with a principle of purposiveness for our faculty of cognition, which is then expressed in the maxims of the power of judgment given above. Now this transcendental concept of a purposiveness of nature is neither a concept of nature nor of freedom, since it attributes nothing at all to the object (of nature), but rather represents the unique way in which we must proceed in reflection on the objects of nature with the aim of a thoroughly interconnected experience, consequently it is a subjective principle (maxim) of the power of judgment.47

Kant not only claims to deduce the reflective concept of the purposiveness of nature but also, as he adds following this passage, “the necessity of assuming it as a transcendental principle of cognition” (my emphasis).48 He says his principle “represents the unique way in which we must proceed in reflection on the objects of nature” (my emphasis). This “is neither a concept of nature nor a concept of freedom,” because reflective judgment suspends the application of both understanding and reason and thus suspends the determination of both the realm of nature and the realm of morality. However, what is determined is that the unity of nature “must still necessarily be presupposed and assumed, for otherwise no thoroughgoing interconnection of empirical cognitions into a whole of experience would take place” (my emphasis). Kant stipulates that the necessity of this unity of nature must be thought beyond the determination of nature through the categories of the understanding:

The understanding is of course in possession a priori of universal laws of nature, without which nature could not be an object of experience at all; but still it requires in addition a certain order of nature in its particular laws, which can only be known to it empirically and which from its point of view are contingent. These rules, without which there would be no progress from the general analogy of a possible experience in general to the particular, it must think as laws (i.e., as necessary), because otherwise they would not constitute an order of nature, even though it does not and never can cognize their necessity.49

In addition to the universal laws of nature provided by the categories, we must think a unified order of particular laws of nature (beyond the determinations of the understanding), and we must think these laws as necessary, even if we can never cognize them as such (they are only known to the understanding empirically, and from its point of view are contingent).

What is in evidence here is a dogmatism of subjective rather than objective determination. Again, the transcendental concept of the purposiveness of nature “represents the unique way in which we must proceed in reflection on the objects of nature.” Kant presents this as a “deduction,”50 but in fact the reasoning is covertly inductive: because we know from experience there is a unity of experience, there must be a unity of nature. Because our experience of nature has been unified, nature must necessarily be ordered by laws that unify its order. Because the a priori laws of nature provided by our understanding cannot, on their own, account for the unified interconnection of their determinations, there must be an order of particular laws beyond them, and these must be necessary. The Critique of Pure Reason had set out to resolve the problem of induction by deducing universal, a priori laws of nature belonging to the faculty of understanding, which accounted, on transcendental grounds, for the attribution of constant conjunction to relations of cause and effect that Hume had found wanting on either rational or empirical grounds. But in the Critique of the Power of Judgment, we find that Kant’s purported resolution to the problem of induction requires a supplement, stipulating the reflective necessity of assuming necessary laws (beyond those of the understanding) securing an order of nature which enables a transition from possible experience in general to particular experience. There must be necessary laws ordering the unity of experience because there is a unity of experience. But the ground of such an induction—for it is a disguised induction—is exactly what Hume had demanded. Far from solving the problem Hume had formulated, Kant ends up reproducing its aporia as a “merely reflecting” judgment that is not objectively but subjectively dogmatic.

We must be attentive to what, according to Kant, has to be thought. Kant deploys reason not determine the in-itself directly, but to determine the reflective necessity of thinking the laws of the in-itself as necessary, though we can only experience them as contingent. Kant must say that this has to be thought, because otherwise the problem of induction would be unresolved; we would not have a subjective principle securing the unified order of nature for reflective judgment. But the grounds for the rational judgment producing this principle are empirical grounds (x is and has been the case; y is necessary for x to be the case; so y must be the case), which are acknowledged as insufficient for the judgment of necessity. Kant ignores the speculative problem of whether it is in fact necessary to think that the unified order of nature we experience is secured by necessary laws. The persistence of the unified order of nature we experience could be contingent; it may be contingent that a unity of laws has obtained—which is exactly the judgment our experience could ground. That is, we do not have to think what Kant says we must think. In fact, there is no reason to think it. And this is exactly what “that acute man,” David Hume, had pointed out in the first place.


Speculation enters into the terrain of what has to be thought and interrogates its determinations. Is it true that we have to think what Kant says we must think? How would the absolute idealist reply? How would the Kantian then have to reply to the absolute idealist? How does the history of thought—the rigorous articulation of its movement between systematic determinations—impose new constraints upon what we have to think? The rationalism of speculative thought implies a critical vocation, which it should not abjure. Hegel refers to his speculative method in the Science of Logic as a “true critique” because it investigates the determinations of reflection on their own ground, in the medium of their self-interrogating movement, thus producing an immanent rather than transcendental method of criticism. Such critique involves a rational reflection upon the experience of thinking, and thus also an empirical investigation of the determinations of reason—observing, cancelling, and developing these as they unfold. In Chapter 3, I develop a rationalist empiricist interpretation of Hegel’s dialectic, positioning it as a form of speculative critique. But in Chapter 4, I also attend to the dereliction of Hegel’s own critical method at pivotal moments in the Phenomenology and the Logic, showing how the violation of imminent critique is due to a certain treatment of the relation between time and the whole in Hegel’s philosophy. The critical delimitation of Hegel’s speculative ontology thus requires a transition from speculative idealism to speculative materialism, and I argue that producing precisely this critical delimitation is the burden of Meillassoux’s doctoral dissertation. Here we will see, as in Chapter 2, that the defense of materialism against idealism depends upon an alignment of the relationship between rationalism and empiricism that can preserve the critical function of speculation, rather than sever speculation from critique.

The difficulty with Kant’s principle of reflective judgment (the purposiveness of nature) is that he wants to ground philosophical reflection concerning the empirical interconnection of nature upon a rational principle that is supposedly required as a subjective maxim. Thus reflective judgment rationally subordinates the contingency of experience to the necessity of laws that we can never experience but that we must think. When Meillassoux shows, through his Cantorian treatment of the statistical resolution of the problem of induction, that it is rationally feasible to sustain a thesis of unsubordinated contingency (to think that the necessity of laws is not required to account for the empirical unity and regularity of laws) he unburdens philosophy of grounding the relation between the empirical and the rational. The rational thesis of absolute contingency does not ground reflection upon the empirical regularity of nature; rather, it distinguishes the ontological order of absolute contingency (thought by philosophy) from the ontic order of empirical regularities (explored by science). The speculative has a critical function, insofar as it preserves the autonomy of science against the pretension of (transcendental) philosophy to ground scientific knowledge. And this critique has a speculative function insofar as it preserves the autonomy of philosophy to think the ontological in a manner that is not delimited by empirical science (this is the very criterion of distinction between the ontological and the ontic).

Does this not simply separate the empirical (science) from the rational (philosophy)? Was it not our project to think the productivity of their methodological relation? But what I have tried to show is that science itself involves a mutually critical and productive relationship between reason and experience; Bachelard’s epistemology theorizes science as not simply empiricist but also profoundly rationalist. And philosophical speculation itself, as I try to show in Chapters 2 (Meillassoux) and 3 (Hegel), involves an alternation between the experience of what happens in thought and rational determinations of what has to be said. Indeed, this alternation is not only internal to the speculative arguments of particular thinkers, but also historical in its dynamism. Thus, both “empirical” science and “rational” speculation involve a transmutation of epistemological values between rationalism and empiricism. Part of the burden of speculative critique—against the grounding operations of transcendental critique—is to sustain the autonomy of science and philosophy, according them their own terrain (ontic/ontological) while also thinking their consistency. I hope to show that this distribution of the relation between science and philosophy has important consequences for understanding the relation between idealism and materialism.

That is finally the burden of the chapters that follow: to show how materialism relies upon the powers of speculative critique made possible by what I call, after Althusser, rationalist empiricism. I pursue that project across chapters on methodological exceptions in Descartes and Hume (Chapter 1), on the Althusserian criteria of materialism inherited by Meillassoux (Chapter 2), on the ungrounded, genetic epistemology of Hegel’s Science of Logic (Chapter 3), on the displacement of Hegel’s speculative idealism by Meillassoux’s speculative materialism (Chapter 4), on the metrological redefinition of the kilogram considered through Hegel’s theory of measure (Chapter 5), on contemporary digital photography considered through Whitehead’s theory of prehensions (Chapter 6), on the recessed concept of “structure” in Plato’s Timaeus (Chapter 7), on the relation of Badiou’s theory of the subject to the problem of induction (Chapter 8), on the criterion of immanence in communist theory (Chapter 9), and on the concept of “separation” (Scheidung) as the crux of the rationalist and empiricist dimensions of Marx’s Capital (Chapter 10). Thus the book develops an account of rationalist empiricism relevant not only to ancient, modern, and contemporary philosophy but also to art and political theory.

These chapters are organized into four sections focusing primarily upon (I) epistemology; (II) ontology; (III) “structure” in science, art, and philosophy; and (IV) political theory. Among these, the role of the third section of the book requires further explanation. In these chapters on metrology (Chapter 5), digital photography (Chapter 6), and Plato (Chapter 7), I offer examples of how thinking in terms of rationalist empiricism might illuminate practices in contemporary science and art, and I then pursue a concept of structure latent in the Timaeus that I view as consonant with those examples. What unifies these chapters is their common concern with the codetermination of the material and the ideal. I am interested in how rationally determined quantities and structures both emerge from and are inscribed within material objects and devices, while configurations of experience enabled by the latter give rise to the new possibilities of rational determination. Rather than “apply” the concept of structure I derive from Plato to my engagements with the redefinition of the kilogram and the art practice of Nicolas Baier, I lead with these case studies and then position a reading of Plato within the field of conceptual problems they raise, while offering a Coda at the end of Part III to render legible the retroactive relevance of the concept of structure derived from the Timaeus to the two previous chapters. Indeed, Chapter 7 was composed from the perspective of theoretical questions raised by those previous chapters, and many of the philosophical questions I pursue in this book came into focus not only through my reading of Bachelard, Althusser, Meillassoux, Hegel, or Marx but also and equally from studies of contemporary scientific practice and my encounter with Nicolas Baier’s photography. Thus, I hope Chapters 5 and 6, on science and art, will not be viewed as digressions from the main line of the philosophical argument, but rather as central to its genesis and articulation. The attention of those chapters to concrete practices is integral to my own effort to mediate the claims of reason and experience.

I want to emphasize that the term “rationalist empiricism” is not intended to promulgate some kind of theoretical brand name or methodological school. Insofar as it relies upon the methodological gap between rationalism and empiricism in order to sustain the critical implications of each for the other, rationalist empiricism is not itself a unified method. Rather, it is an orientation toward philosophical problems that seeks to intervene in and unsettle the methodological unity of the tradition. It is also an orientation toward political problems that seeks to intervene in and unsettle any programmatic unity of theory and praxis. Taking up such problems through their relation to the tradition involves engaging contemporary texts, the history of philosophy, and political theory not only in terms of one’s own “position,” but in terms of certain methodological approaches that do not necessarily cohere into a position or align with a single philosophical school. Relations among genuinely different forms of rationalist empiricism will emerge in the interstices of the chapters that follow, in ways that will often remain implicit. Perhaps there is an important relationship between Hegel’s method and Althusserian epistemology that the latter would come to disavow; perhaps there is an unspoken structuralist materialism in Plato’s Timaeus that is obliquely resonant with the operations of contemporary digital photography and computational modeling; perhaps recent developments in communist theory share more with epistemological debates in contemporary philosophy than one might imagine; perhaps Whitehead’s process philosophy is closer to Bachelard’s “rationalist” philosophy of science than one might have thought. The implications of these possibilities, latent in the constellation of chapters that follows, will not always be directly spelled out. What interests me are the different configurations rationalist empiricism can exhibit and how such an orientation can traverse real discrepancies between philosophical priorities and positions, transforming itself in the process.

Of the figures I engage with, it is Whitehead to whom I wish I could have devoted more sustained attention, given his import for my thinking about philosophical speculation. But at least I can close this introduction with the passage from Process and Reality that best formulates the vocation of speculative critique. Indeed, it is the finest definition of philosophy that I know:

Philosophy is the self-correction by consciousness of its own initial excess of subjectivity. Each actual occasion contributes to the circumstances of its origin additional formative elements deepening its own peculiar individuality. Consciousness is only the last and the greatest of such elements by which the selective character of the individual obscures the external totality from which it originates and which it embodies. An actual individual of such higher grade, has truck with the totality of things by reason of its sheer actuality; but it has attained its individual depth of being by a selective emphasis limited to its own purposes. The task of philosophy is to recover the totality obscured by the selection.51

The individual originates from and embodies the external totality. It “has truck with the totality of things by reason of its sheer actuality.” Consciousness is a recently evolved element by which the selective character of the individual pursues its own purposes, thus deepening its individual being but obscuring the totality from which it emerges and in which it inheres. Philosophy is the self-correction by consciousness of this excess of subjectivity. The critical dimension of speculative thought is this self-correction, the delimitation of that selective emphasis by which consciousness obscures external totality. The totality is here preserved as external, even though we embody and originate from it. Yet it can be recovered by philosophy, through the self-correction of the excessive subjectivity of consciousness. And we can say that while empiricism engages the experience of the “sheer actuality” through which we are embedded in the external totality, rationalism delimits the selective emphasis by which our consciousness is constrained. Thus both are required, countering and amplifying one another, in order for philosophy to pursue its speculative labor in concert with critique. We should note as well that in his speculative thinking of the “totality,” Whitehead decompletes its conceptualization as the whole, noting that “the community of actual things … is an incompletion in process of production.”52 In recovering the totality obscured by the selection, one may recover its incompletion as well, deconstituting the totality as not-all by going beyond the subjective limit that would leave the very question of the whole indeterminate.

Self-correction of subjectivity; empirical embeddedness in actuality; rational overcoming of selective consciousness; recovery of totality; decompletion of the whole: Whitehead formulates the essential elements of speculative critique that will be pursued in what follows. I hope to show that the materialism of critique, within and through speculation, depends upon a mutual interruption of reason and experience across a gap that is never resolved into a synthesis or covered by a ground. The perpetual experience of this interruption, and the constantly renewed thinking of its consequences, is the practice of rationalist empiricism.



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