4
This chapter deals with arguing well, recognizing fallacies, avoiding inconsistencies, developing your own arguments, and analyzing arguments that you read.
4.1 Good arguments
A good argument, to be logically correct and fulfill the purposes for which we use arguments, should:
1. be deductively valid (or inductively strong) and have premises all true;
2. have its validity (or inductive strength) and truth-of-premises be as evident as practically possible to the parties involved;
3. be clearly stated (using understandable language and making clear what the premises and conclusion are);
4. avoid circularity, ambiguity, and emotional language; and
5. be relevant to the issue at hand.
If you fulfill these, then you’re arguing well.
First, a good argument should be deductively valid (or inductively strong – see Chapter 5) and have premises all true. We often criticize an argument by trying to show that the conclusion doesn’t follow from (or isn’t supported by) the premises, or that one or more of the premises are false.
Second, a good argument should have its validity (or inductive strength) and truth-of-premises be as evident as practically possible to the parties involved. Arguments are less effective if they presume premises that others see as false or controversial. Ideally, we’d like to use only premises that everyone will accept as immediately obvious; but in practice, this is too high an ideal. We often appeal to premises that will only be accepted by those of similar political, religious, or philosophical views. And sometimes we appeal to hunches, like “I can get to the gun before the thief does”; while not ideal, this may be the best we can do at a given moment.
Third, a good argument should be clearly stated; it should use understandable language and make clear what the premises and conclusion are. Obscure or overly complex language makes reasoning harder to grasp.
When we develop an argument, a good strategy is to put it on paper in a 0052 preliminary way and then reread it several times, trying to make improvements. Try to express the ideas more simply and clearly, and think how others may object or misunderstand. Often ideas first emerge in a confused form; clarity comes later, after much hard work. While mushy thinking is often unavoidable in the early development of an idea, it’s not acceptable in the final product.
People often argue without making clear what their premises and conclusions are; sometimes we get stream-of-consciousness ramblings sprinkled with an occasional “therefore.” While this is unacceptable, a good argument needn’t spell everything out; it’s often fine to omit premises that are obvious to the parties involved. If I’m hiking on the Appalachian Trail, I might say to my hiking partner: “We can’t still be on the right trail, since we don’t see white blazes on the trees.” This is fine if my partner knows that we’d see white blazes if we were on the right trail; then the full argument would be pedantic:
· We don’t see white blazes on the trees.
· If we were still on the right trail, then we’d see white blazes on the trees.
· ∴ We aren’t still on the right trail.
In philosophy, it’s often wise to spell out all our premises, since unstated ideas are often crucial but unexamined. Suppose someone argues: “We can’t be free, since all our actions are determined.” This assumes the italicized premise:
· All human actions are determined.
· No determined action is free.
· ∴ No human actions are free.
We should be aware that we’re assuming this controversial premise.
So a good argument should be valid (or inductively strong) and have premises all true, this validity/strength and truth should be as evident as practically possible, and it should be clearly stated. Our final conditions say that the argument should (4) avoid circularity, ambiguity, and emotional language; and (5) be relevant to the issue at hand. Five common fallacies tie into these final conditions.
Our first fallacy is circularity:
An argument is circular if it presumes the truth of what is to be proved.
A series of arguments is circular if it uses a premise to prove a conclusion – and then uses that conclusion to prove the premise.
“The soul is immortal because it can’t die” is circular; since the premise just repeats the conclusion in different words, the argument takes for granted what it’s supposed to prove. A circular series of arguments might say: “A is true because B is true, and B is true because A is true.” A circular argument is also said to be question begging; this differs from the new (and confusing) usage in 0053 which “begging a question” means “raising a question.”
Here’s a second fallacy, and a crude argument that exemplifies it:
An argument is ambiguous if it changes the meaning of a term or phrase within the argument.
· Love is an emotion.
· God is love.
· ∴ God is an emotion.
Premise 1 requires that we take “love” to mean “the feeling of love” – which makes premise 2 false or doubtful. Premise 2 requires that we take “love” to mean “a supremely loving person” or “the source of love” – which makes premise 1 false or doubtful. We can have both premises clearly true only by shifting the meaning of “love.” Ambiguity is also called equivocation.
Unclear sentence structures can bring ambiguities. For example, “pretty little girls’ camp” can mean “camp for little girls who are pretty,” “pretty camp for little girls,” or “pretty camp that is little and for girls.”
It’s important to avoid emotionally slanted terms when we reason:
To appeal to emotion is to stir up feelings instead of arguing in a logical manner.
Students, when asked to argue against a theory, often just describe the theory in derogatory language; so a student might dismiss Descartes by calling his views “superficial” or “overly dualistic.” But such verbal abuse doesn’t give any reason for thinking a view wrong. Often the best way to argue against a theory is to find some false implication and then reason as follows:
· If the theory is true, then this other thing also would be true.
· This other thing isn’t true.
· ∴ The theory isn’t true.
Recall that an argument consists of premises and a conclusion.
Our last condition says that a good argument must be relevant to the issue at hand. A clearly stated argument might prove something and yet still be defective, since it may be beside the point in the current context:
An argument is beside the point if it argues for a conclusion irrelevant to the issue at hand.
Hitler, when facing a group opposed to the forceful imposition of dictatorships, shifted their attention by attacking pacifism; his arguments, even if sound, were beside the point. Such arguments are also called red herrings, after a practice used in training hunting dogs: a red herring fish would be dragged across the trail to 0054 distract the dog from tracking an animal. In arguing, we must keep the point at issue clearly in mind and not be misled by a smelly fish.
Students sometimes use this “beside the point” label too broadly, to apply to almost any fallacy. This fallacy isn’t about the premises being irrelevant to the conclusion; instead, it’s about the conclusion (regardless of whether it’s proved) being irrelevant to the issue at hand. Suppose a politician is asked “Where do you stand about the proposed tax cuts?” but evades answering, instead shifting our attention to the need for a strong military. These statements are beside the point, since they don’t answer the question.
One common form of this fallacy has its own name:
A straw man argument misrepresents an opponent’s views.
This is common in politics. Candidate A for mayor suggests cutting a few seldom-used stations on the rapid transit system. Then candidate B’s campaign ad expresses shock that A wants to dismantle the whole transit system, which so many citizens depend on; the ad attacks, not what A actually holds, but only a “straw man” – a scarecrow of B’s invention. Campaign ads and speeches that distort an opponent’s view have recently got so bad that “fact checkers” and “truth squads” have arisen to point out misleading language and downright falsehoods – regardless of which side engages in these.
Again, a good argument is valid (or inductively strong) and has premises all true; has this validity/strength and truth be as evident as practically possible; is clearly stated; avoids circularity, ambiguity, and emotional language; and is relevant to the issue. Good arguments normally convince others, but not always. Some people aren’t open to rational argument on many issues; some believe that the earth is flat, despite good arguments to the contrary. And bad arguments sometimes convince people; Hitler’s beside the point fallacy and the candidate’s straw man fallacy can mislead and convince. Studying logic can help protect us from bad reasoning. The better we can distinguish good from bad reasoning, the less will politicians and others be able to manipulate people.
“Proof” is roughly like “good argument.” But we can prove something even if our argument is unclear, contains emotional language, or is irrelevant to the issue at hand. And a proof must be very strong in its premises and in how it connects the premises to the conclusion; for the latter reason, it seems wrong to call inductive arguments “proofs.” So we can define a proof as a non-circular, non-ambiguous, deductively valid argument with clearly true premises. A refutation of a statement is a proof of the statement’s denial.
“Proof” can have other meanings. Chapters 7 to 14 use “proof” in the technical sense of “formal proof,” to cover logical derivations that follow specified rules. And Exercise 3.5a explained that “prove” could have various meanings in the question, “Can we prove that there are external objects?” The word “proof” has a cluster of related meanings. 0055
“Prove” and “refute” are often misused. These properly apply only to successful arguments. A proof shows that something is true, and a refutation shows that something is false. Avoid saying things like “Hume proved this, but Kant refuted him.” This is self-contradictory, since it implies that Hume’s claim is both true and false – and that Hume showed it was true and Kant showed it was false. It’s better to say “Hume argued for this, but Kant criticized his reasoning.”
4.2 Informal fallacies
A fallacy is a deceptive error of thinking; an informal fallacy is a fallacy not covered by some system of deductive or inductive logic. In working out the conditions for a good argument, we introduced five informal fallacies: circular, ambiguous, appeal to emotion, beside the point, and straw man. We now add thirteen more, in three groups. While this book covers most common fallacies, there are many others that aren’t listed here.
Our first group includes six fallacies expressed in a premise–conclusion format. This first appeals to our herd instincts:
Appeal to the crowd
· Most people believe A.
· ∴ A is true.
· Most people think Wheaties is very nutritious.
· ∴ Wheaties is very nutritious.
Despite what people think, Wheaties cereal might have little nutritional value. Discovering its nutritional value requires checking its nutrient content; group opinion proves nothing. While we all recognize the fallacy here, group opinion still may influence us. Humans are only partially rational.
The opposition fallacy comes from dividing people into “our group” (which has the truth) and “our opponents” (who are totally wrong):
Opposition
· Our opponents believe A.
· ∴ A is false.
· Those blasted liberals say we should raise taxes.
· ∴ We shouldn’t raise taxes.
The problem here is that our opponents may be right.
The genetic fallacy dismisses a belief on the basis of its origin:
Genetic fallacy
· We can explain why you believe A.
· ∴ A is false.
· Any psychologist would see that you believe A because of such and such.
· ∴ A is false.
One who has superficially studied a little psychology may dismiss another’s 0056 views in this way. An appropriate (but nasty) reply is, “And what is the psychological explanation for why you confuse psychological explanations with logical disproofs?” To show a belief to be false, we must argue against the content of the belief; it’s not enough to explain how the belief came to be.
This next one has two closely related forms:
Appeal to ignorance
· No one has proved A.
· ∴ A is false.
· No one has disproved A.
· ∴ A is true.
· No one has proved there’s a God.
· ∴ There’s no God.
· No one has proved there’s no God.
· ∴ There’s a God.
Something not proved might still be true, just as something not disproved might still be false. An “appeal to ignorance” must have one of these forms; it’s not just any case where someone speaks out of ignorance.
This next one uses a Latin name for “after this therefore because of this”:
Post hoc ergo propter hoc
· A happened after B.
· ∴ A was caused by B.
· Paul had a beer and then got 104% on his logic test.
· ∴ He got 104% because he had beer.
The premise was true (there were bonus points). Some students concluded: “So if I have a beer before the test, I’ll get 104%” and “If I have a six-pack, I’ll get 624%.” Proving causal connections requires more than just the sequence of two factors; the factors might just happen to have occurred together. It’s not even enough that factors always occur together; day always follows night, and night always follows day, but neither causes the other. Proving causal connections is difficult (see Mill’s methods in §5.7).
This next one is also called division–composition:
Part–whole
· This is F.
· ∴ Every part of this is F.
· Every part of this is F.
· ∴ This is F.
· My essay is good.
· ∴ Every sentence of my essay is good.
· Every sentence of my essay is good.
· ∴ My essay is good.
The first argument is wrong because an essay might be good despite having some poor sentences. The second is wrong because each sentence of the essay might be good without the essay as a whole being good; the fine individual sentences might not make sense together. So something might be true of a whole without being true of the parts, or true of the parts without being true of the whole. A property that characterizes a whole but not any parts is sometimes called an emergent property: being alive is an emergent property possessed by a cell but not by any component molecules – and water may be clear and wet without 0057 individual H2O molecules being clear or wet. More controversially, some say thinking is an emergent property possessed by the brain but not by its cells.
In rare cases, these fallacy forms might be abbreviated forms of good reasoning. Suppose you know that people in your society almost never have false beliefs; then this “appeal to the crowd” could be correct inductive reasoning:
· Almost always, what most people in my society believe is true.
· Most people in my society believe A.
· That’s all we know about the matter.
· ∴ Probably A is true.
Or suppose you know that your opponent Jones is always wrong. Then this could be sound reasoning: “Everything Jones says is false, Jones says A, so A is false.” But correct forms of these six fallacy forms are unusual in real life.
Our next group has three types of reasoning with correct and fallacious forms. This first type of reasoning appeals to expert opinion:
Appeal to authority – correct form:
· X holds that A is true.
· X is an authority on the subject.
· The consensus of authorities agrees with X.
· ∴ There’s a presumption that A is true.
Incorrect forms omit premise 2 or 3, or conclude that A must be true.
This one has the correct form:
· Your doctor tells you A.
· She’s an authority on the subject.
· The other authorities agree with her.
· ∴ There’s a presumption that A is true.
This conclusion means that we ought to believe A unless we have special evidence to the contrary. If the doctor is a great authority and the consensus of authorities is large, then the argument becomes stronger; but it’s never totally conclusive. All the authorities in the world might agree on something that they later discover to be wrong; so we shouldn’t think that something must be so because the authorities say it is. It’s also wrong to appeal to a person who isn’t an authority in the field (a sports hero endorsing coffee makers, for example). And finally, it’s weak to appeal to one authority (regarding the safety of nuclear energy, for example) when the authorities disagree widely. The appeal to authority can go wrong in many ways. Yet many of our trusted beliefs (that Washington was the first US president, for example, or that there’s such a country as Japan) rest quite properly on the say so of others.
An “authority” might be a calculator or computer instead of a human. My calculator has proved itself reliable, and it gives the same result as other reliable calculators. So I believe it when it tells me that 679 • 177 = 120,183.0058
This next one uses a Latin name for “against the person” (which is opposed to ad rem, “on the issue”):
Ad hominem – correct form:
· X holds that A is true.
· In holding this, X violates legitimate rational standards (for example, X is inconsistent, biased, or not correctly informed).
· ∴ X isn’t fully reasonable in holding A.
Incorrect forms use factors irrelevant to rational competence (for example, X is a member of a hated group or beats his wife) or conclude that A is false.
This one has the correct form:
· Rick holds that people of this race ought to be treated poorly.
· In holding this, Rick is inconsistent (because he doesn’t think that he ought to be treated that way if he were in their exact place) and so violates legitimate rational standards.
· ∴ Rick isn’t fully reasonable in his views.
A “personal attack” argument can be either legitimate or fallacious. In our example, we legitimately conclude that Rick, because he violates rational standards, isn’t fully reasonable in his beliefs. It would be fallacious to draw the stronger conclusion that his beliefs must be wrong; to show his beliefs to be wrong, we must argue against the beliefs, not against the person. A more extreme ad hominem was exemplified by Nazis who argued that Einstein’s theories must be wrong since he was Jewish; being Jewish was irrelevant to Einstein’s competence as a scientist.
This next form of reasoning lists and weighs reasons for and against:
Pro–con – correct form:
· The reasons in favor of act A are ….
· The reasons against act A are ….
· The former reasons outweigh the latter.
· ∴ Act A ought to be done.
Incorrect form:
· The reasons in favor of act A are …
· ∴ Act A ought to be done.
This one has the correct form:
· The reasons in favor of getting an internal-frame backpack are ….
· The reasons against getting an internal-frame backpack are ….
· The former reasons outweigh the latter.
· ∴ I ought to get an internal-frame backpack.
People sometimes make decisions by folding a piece of paper in half and listing reasons in favor on one side and reasons against on the other; then they decide intuitively which side has stronger (not necessarily more) reasons. This method forces us to look at both sides of an issue. In the incorrect form, we just look at half the picture; we say that you should do this (because of such and such advantages) or that you shouldn’t do it (because of such and such disadvantages). 0059 This fallacy is also called “one-sided” or “stacking the deck.”
We can expand our three correct forms into standard inductive and deductive arguments. A correct appeal to authority becomes a strong inductive argument if we add this inductively confirmed premise: “The consensus of authorities on a subject is usually right.” Correct ad hominem arguments become deductively valid if we add: “Anyone who, in believing A, violates legitimate rational standards is thereby not fully reasonable in believing A.” And correct pro–con arguments become deductively valid if we add: “If the reasons in favor of A outweigh the reasons against A, then A ought to be done.”
Our final group has four miscellaneous fallacies. Here’s the first fallacy (which is also called false dilemma):
Black-and-white thinking oversimplifies by assuming that one or another of two extreme cases must be true.
One commits this fallacy in thinking that people must be logical or emotional, but can’t be both. My thesaurus lists these terms as having opposite meanings; but if they really had opposite meanings, then no one could be both at once – which indeed is possible. In fact, all four combinations are common:
· logical and emotional
· logical and unemotional
· illogical and emotional
· illogical and unemotional
People who think in a black-and-white manner prefer simple dichotomies, like logical-emotional, capitalist-socialist, or intellectual-jock. Such people have a hard time seeing that the world is more complicated than that.
This next fallacy is also called hasty generalization:
To use a false stereotype is to assume that the members of a certain group are more alike than they actually are.
People commit this fallacy in thinking that all Italians exist only on spaghetti, that all New Yorkers are uncaring, or that all who read Karl Marx want to overthrow the government. False stereotypes can be detrimental to the stereotyped. A study compared scores on a math test of two otherwise identical groups of young girls; just the first group was told beforehand that girls are genetically inferior in math – and this group did much worse on the test.
This next fallacy substitutes violence for reasoning:
To appeal to force is to use threats or intimidation to get a conclusion accepted.
0060 A parent might say, “Just agree and shut up!” Parents and teachers hold inherently intimidating positions and are often tempted to appeal to force.
This last fallacy is also called trick question:
A complex question is a question that assumes the truth of something false or doubtful.
The standard example is: “Are you still beating your wife?” A “yes” implies that you still beat your wife, while a “no” implies that you used to beat her. The question combines a statement with a question: “You have a wife and used to beat her; do you still beat her?” The proper response is: “Your question presumes something that’s false, namely that I have a wife and used to beat her.” Sometimes it’s misleading to give a “yes” or “no” answer.
4.2a Exercise: LogiCola R
Identify the fallacies in the following examples. Not all are clear-cut; some examples are controversial and some commit more than one fallacy. All the examples here are fallacious. Use these labels to identify the fallacies:
aa = appeal to authority
ac = appeal to the crowd
ae = appeal to emotion
af = appeal to force
ah = ad hominem
ai = appeal to ignorance
am = ambiguous
bp = beside the point
bw = black and white
ci = circular
cq = complex question
fs = false stereotype
ge = genetic
op = opposition
pc = pro–con
ph = post hoc
pw = part–whole
sm = straw man
This sports hero advertises a popcorn popper on TV. He says it’s the best popcorn popper, so this must be true.
This is aa (appeal to authority). There’s no reason to think the sports hero is an authority on popcorn poppers.
1. Are you still wasting time with all that book-learning at the university?
2. The Bible tells the truth because it’s God’s word. We know the Bible is God’s word because the Bible says so and it tells the truth.
3. You should vote for this candidate because she’s intelligent and has much experience in politics.
4. The Equal Rights Amendment was foolish because its feminist sponsors were nothing but bra-less bubbleheads.
5. No one accepts this theory anymore, so it must be wrong.
6. Either you favor a massive arms buildup, or you aren’t a patriotic American.
7. The president’s veto was the right move. In these troubled times we need decisive leadership, even in the face of opposition. We should all thank the president for his courageous move.
8. Each member of this team is unbeatable, so this team must be unbeatable. 0061
9. My doctor told me to lose weight and give up smoking. But she’s an overweight smoker herself, so I can safely ignore her advice.
10.Belief in God is explained in terms of one’s need for a father figure; so it’s false.
11.There are scientific laws. Where there are laws there must be a lawgiver. Hence someone must have set up the scientific laws to govern our universe, and this someone could only be God.
12.The lawyer for the defense claims that there’s doubt that Smith committed the crime. But, I ask, are you going to let this horrible crime go unpunished because of this? Look at the crime; see how horrible it was! So you see clearly that the crime was horrible and that Smith should be convicted.
13.Free speech is for the common good, since unrestrained expression of opinion is in people’s interest.
14.This is a shocking and stupid proposal. Its author must be either a dishonest bum or a complete idiot.
15.Aristotle said that heavy objects fall faster than light ones, so it must be true.
16.Each of these dozen cookies (or drinks) by itself isn’t harmful; one little one won’t hurt! Hence having these dozen cookies (or drinks) isn’t harmful.
17.Before Barack Obama became the Democratic candidate for US president, he ran in a series of primary elections. He noted that he played basketball before the Iowa primary, and then won the vote, while he neglected to play before the New Hampshire primary, and then lost. He concluded (in jest) “At that point I was certain that we had to play on every primary.”
18.Only men are rational animals. No woman is a man. Therefore no woman is a rational animal.
19.I’m right, because you flunk if you disagree with me!
20.The discriminating backpacker prefers South Glacier tents.
21.Those who opposed the war were obviously wrong; they were just a bunch of cowardly homosexual Communists.
22.We should legalize gambling in our state, because it would bring in new tax revenue, encourage tourists to come and spend money here, and cost nothing (just the passing of a new law).
23.Do you want to be a good little boy and go to bed?
24.This man is probably a Communist. After all, nothing in the files disproves his Communist connections.
25.People who read Fortune magazine make a lot of money. So if I subscribe to Fortune, then I too will make a lot of money.
26.Feminists deny all difference between male and female. But this is absurd, as anyone with eyes can see.
27.Each part of life (eyes, feet, and so on) has a purpose. Hence life itself must have a purpose.
28.So you’re a business major? You must be one of those people who care only about the almighty dollar and aren’t concerned about ideas.
29.My opponent hasn’t proved that I obtained these campaign funds illegally. So we must conclude that I’m innocent.
30.Those dirty Communists said that we Americans should withdraw from the Panama Canal, so obviously we should have stayed there. 0062
31.Karl Marx was a personal failure who couldn’t even support his family, so his political theory must be wrong.
32.Religion originated from myth (which consists of superstitious errors). So religion must be false.
33.Suzy brushed with Ultra Brilliant and then attracted boys like a magnet! Wow – I’m going to get some Ultra Brilliant. Then I’ll attract boys too!
34.Did you kill the butler because you hated him or because you were greedy?
35.My parents will be mad at me if I get a D, and I’ll feel so stupid. Please? You know how I loved your course. I surely deserve at least a C.
36.Miracles are impossible because they simply can’t happen.
37.I figure that a person must be a Communist if he doesn’t think the American free-enterprise system is flawless and the greatest system in the world.
38.Everyone thinks this beer is simply the best. So it must be the best.
39.We ought to oppose this, since it’s un-American.
40.Practically every heroin addict first tried marijuana. Therefore, marijuana causes heroin addiction.
41.Most college students are mainly concerned with sports, liquor, and sex. So this is normal. But Duane is mainly concerned with poetry. So he must be abnormal and thus unhealthy.
42.Each of the things in my backpack is light, so my loaded backpack must be light.
43.You’re wrong in disagreeing with me, because what I said is true.
44.Everyone thinks the Democrat is the better candidate, so it must be true.
45.We should reject Mendel’s genetic theories, since he was a monk and thus couldn’t have known anything about science.
46.Every time I backpack it seems to rain. I’m going backpacking next week. So this will cause it to rain.
47.It hasn’t been proved that cigarettes are dangerous, so it’s only reasonable to conclude that they aren’t dangerous.
48.In a commercial filled with superb scenery, sexy girls, and soft music: “Buy a Ford Mustang – it’s a super car!”
49.Atheism is absurd. Atheists deny God because they can’t see him. But who has seen electrons either?
50.President George W. Bush was in office for several years, and then the financial crisis occurred in 2008. Therefore the crisis occurred because Bush was in office.
51.Do you support freedom and the unrestricted right to buy weapons?
52.We don’t know how the first forms of life could have emerged by natural causes from the primeval chemical soup that covered the earth. So we must assume that they didn’t emerge by natural causes; so they had to have had a divine origin.
53.Since no atom in this rock is heavy or green, this rock cannot be heavy or green.
54.That car can’t be any good, since it was made in Detroit.
55.All doctors are men with medical degrees. But no woman is a man with a medical degree. Therefore, no woman is a doctor.
56.If you don’t keep quiet about our bank’s dishonest practices, you’re apt to lose your job.
57.A black cat crossed my path, and then later I flunked my logic test. So this proves that black cats are unlucky. 0063
58.Either you respect and agree with your teacher, or you’re insolent and don’t deserve a good grade.
59.In spite of warnings from lifeguards, my girlfriend went swimming without a worry. She said that she didn’t have to worry about man-eating sharks.
60.Will you contribute to our collection for famine relief, or are you insensitive to the suffering of other people?
4.2b Another Fallacy Exercise: LogiCola R
1. When are we going to guarantee all the people of this country the health care that they deserve?
2. When are we going to understand that the government cannot afford to pay for universal health care?
3. The professor’s letter of recommendation said, “I cannot praise this student’s study habits too highly.”
4. No one has proven that humans are causing global warming; so we should assume that the heating of the earth has purely natural causes.
5. Christians are peaceful, Muslims are terrorists.
6. I never had problems with headaches before I studied logic. So studying logic must cause my headaches.
7. This candidate’s ideas are really scary; don’t they make you afraid? I fear what would happen to our country if this candidate were elected.
8. Charles Darwin, who came up with the theory of evolution, presumably thought that his grandfather was a monkey.
9. You ask me why I deposited the company funds in my personal banking account. But why are you so doubtful about my integrity? Don’t you believe that we all need to be more trusting?
10.American military experts testified in the first decade of the 21st century that Iraq was developing weapons of mass destruction; so this must be true.
11.If all persons in a group work to maximize their individual self-interest, then the group is working effectively to maximize its own self-interest.
12.The liberal elite media did it again! Those idiots are out to attack those of us who have solid, pro-American values.
13.My mother demands that I clean up after I make waffles. She is an incredible neatness freak! She wants me to devote my whole life to keeping her kitchen spotless!
14.Liberation theology got some of its concepts (like oppressive social structures) from atheistic Marxists, and so these concepts should be rejected.
15.This backpacking tent is very lightweight, and so this is the one you should get.
16.Everyone knows there ain’t no gold in the Grand Canyon.
17.The Democrats want to raise tax rates on the rich and lower them on the middle class. This is part of their plan to move the country into socialism.
18.No one has given conclusive evidence showing that aliens from outside our planet didn’t land near Roswell in 1947. So we should believe the witnesses who say that they encountered such aliens.
19.You should vote for me because I will lower your taxes.
20.Humans are “hardwired” so that, at least for the most part, they believe in God. So belief in God is rational. 0064
21.Humans are “hardwired” so that, at least for the most part, they believe in God. So belief in God is irrational.
22.The second exam question asked me to describe Aristotle’s approach to ethics. But since I didn’t know anything about this, I instead described Plato’s approach.
23.Those horrible city folk vote Democratic; so we country folk should vote Republican.
24.If you don’t want to suffer an unfortunate accident, you’d better find my client innocent.
25.We should take either all of the Bible literally or else none of literally.
26.Men are logical, women are emotional.
27.Since there’s no good evidence that there’s intelligent life in other parts of the universe, it’s only reasonable to conclude that there’s no such life.
28.Since Martin Heidegger developed many of his ideas when he was a Nazi supporter in Germany, we should disregard his ideas.
29.Gensler, who authored the Routledge Introduction to Logic, wears sandals with socks and claims that this is very fashionable; so this must be so.
30.We shouldn’t listen when this Republican argues for tax relief for the rich; after all, her family was very rich.
31.If you don’t buy some Girl Scout Cookies, I’ll tell everyone how cheap you are.
32.My favorite Russian tennis star claims that Canon cameras are the best; so I plan to get one.
33.Where did you hide the dead body of your murder victim?
34.I read on the Internet that global warming is a hoax; so this must be true.
35.Cheating on exams can’t be wrong; I mean, everyone does it.
36.The Republicans say that they are against “big government.” But they really want to eliminate all social services for those in need, so the rich can become even richer.
37.Last night I shot a burglar in my pajamas. I don’t know how he got into my pajamas.
38.Are you going to admit that you’re wrong?
39.Look at all the bad things that happened to our country while my opponent was in office! If you don’t want to elect an official who’ll bring about such bad things, then you should vote against my opponent.
40.Everything in the universe has a cause; so the universe also has a cause.
41.If you need another reference for my honesty, I can get Mariana Smith to vouch for me. Oh, you’ve never heard of Mariana Smith? Well, I can vouch for her.
42.I installed LogiCola on my computer, and then two weeks later my computer failed. LogiCola must be to blame!
43.So, you ask, which of my campaign promises will have to wait if we don’t have enough funds to fulfill them all? Instead of responding, I’d like to address what’s really troubling the people of this country, namely why the current administration is so dishonest.
44.Either you favor the Republicans or you aren’t patriotic.
45.I had foolish and immature ideas like yours when I was your age.
46.Ancient Romans to Christians: “If you refuse to renounce your faith and worship the gods of Rome, we’ll feed you to the lions.”
47.All logicians are emotionless calculators. 0065
48.When Gensler baked his first batch of cookies, he used very good ingredients. Therefore the cookies that he baked were very good.
49.We shouldn’t listen when this Democrat argues for tax relief for the poor; after all, her family was very poor.
50.God must have created the world, since surely someone must have created it.
51.Most Americans supported President George W. Bush’s invasion of Iraq, so this invasion must have been a good thing.
52.You should take Gensler’s logic course because he has a great sense of humor.
53.If you weren’t so stupid, you’d agree with me.
54.To a junior Member of Congress: “If you don’t vote for this Bill, you’ll never be appointed to any important committees.”
55.Why does my opponent want to lead our country into socialism?
56.Since each cell in the human organism is incapable of thought, thus the human organism itself is incapable of thought.
57.The Volkswagen was first developed by the Nazis, and so it must be an evil car.
58.Those crude country folk support this idea; so we city folk should be against it.
59.Dr Jones, you can’t prove that I didn’t come up independently with the same essay that occurs with word-by-word similarity on the Internet. So you must assume that I’m innocent of plagiarism.
60.Gensler’s logic book is the best. My proof is that it says so inside, on the last problem of §4.2b.
4.3 Inconsistency
Inconsistency is the most important fallacy – the most important deceptive error of thinking. Students writing on philosophical issues for the first time often express inconsistent views, as in this example:
Since morality is relative to culture, no duties bind universally. What’s right in one culture is wrong in another. Universal duties are a myth. Relativism should make us tolerant toward others; we can’t say that we’re right and they’re wrong. So everyone ought to respect the values of others.1
1 See my Ethics: A Contemporary Introduction, 3rd ed. (New York: Routledge, 2018), Chapter 2.
Here the first statement is incompatible with the last:
· “No duties bind universally.”
· “Everyone ought to respect the values of others.”
If everyone ought to respect the values of others, then some duties bind universally. And if no duties bind universally, then neither does the duty to respect the values of others. This inconsistency isn’t trivial; it cuts deeply. The unexamined views that we use to guide our lives are often radically incoherent; putting these views into words often brings out their incoherence. The ancient Greek philosopher Socrates was adept at showing people how difficult it was to 0066 have consistent beliefs on the deeper questions of life.
Inconsistency is common in other areas too. Someone running for political office might talk to environmentalists one day and industrialists the next. Each group might be told exactly what it wants to hear. The first group is told “I’ll support stronger clean-air standards”; the second is told “I’ll try to lower clean-air standards.” We can be sure that the politician, if elected, will violate some of the promises; one can’t fulfill incompatible promises.
We often aren’t aware of our inconsistency. For example, one might believe all three of these:
1. God is good.
2. Predestination is true. (God immediately causes everything that happens.)
3. God damns sinners to eternal punishment.
These three beliefs aren’t inconsistent in themselves. But the person might have other beliefs that add to these three to make an inconsistent set:
· 4. If predestination is true, then God causes us to sin.
· 5. If God causes us to sin and yet damns sinners to eternal punishment, then God isn’t good.
This set of five beliefs is inconsistent. Beliefs 2 and 4 entail “God causes us to sin.” This, with 3 and 5, entails “God isn’t good” – which contradicts 1. So the five beliefs can’t all be true together. Someone who believes all five might not be aware of the inconsistency; the beliefs might not have come together in the person’s consciousness at the same time.
Inconsistency is a sign that our belief system is flawed and that we need to change something. Logic can tell us that our belief system is inconsistent. But it can’t tell us how to rearrange beliefs to regain consistency; that’s up to us.
Controversies often arise when a set of individually plausible statements can’t consistently be combined. Consider this group of statements:
· F = Some human actions are free.
· D = All human actions are determined.
· I = No determined actions are free.
Even though each claim by itself is plausible, the set is inconsistent. If we take any two of the statements as premises, we can infer the denial of the third. Hard determinists take D (determinism) and I (that determinism is incompatible with free will) as premises. They conclude not-F (that we have no free will):
· All human actions are determined.
· No determined actions are free.
· ∴ No human actions are free.
· D
· I
· ∴ Not-F 0067
Indeterminists take F (free will) and I (that determinism is incompatible with free will) as premises. They conclude not-D (the falsity of determinism):
· Some human actions are free.
· No determined actions are free.
· ∴ Some human actions aren’t determined.
· F
· I
· ∴ Not-D
Soft determinists take F (free will) and D (determinism) as premises. They conclude not-I (that determinism isn’t incompatible with free will):
· Some human actions are free.
· All human actions are determined.
· ∴ Some determined actions are free.
· F
· D
· ∴ Not-I
Each of the three arguments has plausible premises. All three arguments are valid, but at most only one of them can have true premises.
The three arguments relate to each other in an interesting way. Each argument is a “turnaround” of the other two. An argument is a turnaround of another argument if each results from the other by switching the denial of a premise with the denial of the conclusion. Here is an example:
Hard determinism
· D
· I
· ∴ Not-F
Indeterminism (switches the denial of a premise with the denial of the conclusion)
· F
· I
· ∴ Not-D
As you’ll see from the exercises, several classical philosophical disputes involve turnaround arguments. In each dispute, we have a set of individually plausible statements that can’t consistently be combined.
A single statement may be inconsistent with itself. A self-refuting statement is a statement that makes such a sweeping claim that it ends up denying itself. Suppose I tell you: “Everything that I tell you is false.” Could this be true? Not if I tell it to you; then it has to be false. The statement refutes itself. Or suppose I say: “I know that there’s no human knowledge.” This couldn’t be true. If it were true, then there would be some human knowledge – thus refuting the claim. A self-refuting claim often starts as a seemingly big, bold insight. The bubble bursts when we see that it destroys itself.
Consistency relates ethical beliefs to actions in a special way. Suppose I believe that this man is bleeding. That belief doesn’t commit me, under pain of inconsistency, to any specific act; how I live can’t be inconsistent with this belief (taken by itself). But suppose I believe that I ought to call the doctor. This ethical belief does commit me, under pain of inconsistency, to action. If I don’t act to call the doctor, then the way I live is inconsistent with my belief. Consistency requires a harmony between our ethical beliefs and how we live. 0068
Many consistency arguments in ethics depend on the universalizability principle, on which nearly all philosophers agree. Universalizability claims that whatever is right (wrong, good, bad, etc.) in one case also would be right (wrong, good, bad, etc.) in any exactly or relevantly similar case, regardless of the individuals involved. Here’s an example adapted from the Good Samaritan parable (Luke 10:30–5). Suppose that, while I’m jogging, I see a man who’s been beaten, robbed, and left to die. Should I help him, perhaps by making a phone call? I think of excuses why I shouldn’t. I’m busy, don’t want to get involved, and so on. I say to myself, “It would be all right for me not to help him.” But then I consider an exactly reversed situation. I imagine myself in his place; I’m the one who’s been beaten, robbed, and left to die. And I imagine him being in my place; he’s jogging, sees me in my sad state, and has the same excuses. I ask myself, “Would it be all right for this man not to help me in this situation? Surely not!” But then I’m inconsistent. What’s all right for me to do to another has to be all right for the other to do to me in an imagined exactly reversed situation.1
1 For more on consistency in ethics, see Chapters 13 and 14 of this present book and Chapters 7 to 9 of my Ethics: A Contemporary Introduction, 3rd ed. (New York: Routledge, 2018).
4.3a Exercise
Construct a turnaround argument based on the three incompatible statements in the box. Include statement C as a premise of your argument.
A. There are no universal duties.
B. Everyone ought to respect the dignity of others.
C. If everyone ought to respect the dignity of others, then there are universal duties.
· If everyone ought to respect the dignity of others, then there are universal duties.
· Everyone ought to respect the dignity of others.
· ∴ There are universal duties.
1. Construct a different turnaround argument based on the three statements in this first box. Again, include statement C as a premise of your argument.
2. Construct a turnaround argument based on the four incompatible statements in this second box. Include statement A as a premise of your argument.
A. If we have ethical knowledge, then either ethical truths are provable or there are self-evident ethical truths.
B. We have ethical knowledge.
C. Ethical truths aren’t provable.
D. There are no self-evident ethical truths.
· 3. Following the directions in 2, construct a second such turnaround argument.
· 4. Following the directions in 2, construct a third such turnaround argument. 0069
· 5. Construct a turnaround argument based on the three incompatible statements in this third box.
A. All human concepts come from sense experience.
B. The concept of logical validity is a human concept.
C. The concept of logical validity doesn’t come from sense experience.
· 6. Following the directions in 5, construct a second such turnaround argument.
· 7. Following the directions in 5, construct a third such turnaround argument.
· 8. If an argument is valid, then is its turnaround necessarily also valid? Argue for the correctness of your answer.
The next seven examples are self-refuting statements. Explain how each self-refutes.
· 9. No statement is true.
· 10. Every rule has an exception.
· 11. One ought not to accept statements that haven’t been proved.
· 12. Any statement whose truth or falsity we can’t decide through scientific experiments is meaningless.
· 13. There’s no such thing as something being “true.” There are only opinions, each being “true for” the person holding it, none being just “true.”
· 14. We can know only what’s been proved using experimental science. I know this.
· 15. It’s impossible to express truth in human concepts.
4.4 Constructing arguments
This book presents many logical tools; these can help turn mushy thinking into clear reasoning. You should use these logical tools where appropriate in your own reading and writing.
Imagine that your ethics teacher gives you this assignment:
Suppose you work for a small company called Mushy Software. You can get a big contract for your company, but only by bribing an official of Enormity Incorporated. Would it be right for you to offer the bribe? Write a paper taking a position on this. Give a clear argument explaining the reasoning behind your answer.
From your study of logic, you know that an argument is a set of statements divided into premises and a conclusion. The assignment tells you to construct a valid argument along these lines:
· [Insert plausible premise.]
· [Insert plausible premise.]
· ∴ Offering the bribe is / isn’t right.
Phrase your argument as clearly and simply as possible, and make sure that it’s 0070 valid in some acceptable logical system. After sketching various arguments, you might arrive at this (which is valid in syllogistic and quantificational logic):
· No dishonest act is right.
· Offering the bribe is a dishonest act.
· ∴ Offering the bribe isn’t right.
When you propose an argument, it’s wise to ask how an opponent could object to it. While the form here is clearly valid, there might be some difficulty with the premises. How could an opponent attack the premises?
One way to attack a universal claim is to find a counterexample:
Counterexample: To refute “all A is B,” find something that’s A but not B; to refute “no A is B,” find something that’s A and also B.
Premise 1 says “No dishonest act is right.” You could refute this by finding an action that’s dishonest and also right. Can you think of any such action? Imagine a case in which the only way to provide food for your starving family is by stealing. Presumably, stealing here is dishonest but also right:
· This act of stealing is a dishonest act.
· This act of stealing is right.
· ∴ Some dishonest acts are right.
This is valid in syllogistic and quantificational logic. So if the premises here are true, then premise 1 of your original argument is false.
Modus tollens gives another simple way to attack a claim:
Modus tollens
To refute claim A, find a clearly false claim B that A implies. Then argue as below:
· If A then B.
· Not-B.
· ∴ Not-A.
Try to find some clearly false claim that one of the premises implies. This argument seems to work:
· If no dishonest act is right, then it wouldn’t be right to steal food for your starving family when this is needed to keep them from starving.
· It would be right to steal food for your starving family when this is needed to keep them from starving.
· ∴ Some dishonest acts are right. 0071
This is valid in propositional logic. If the premises are true, then premise 1 of your original argument is false. This modus tollens objection is similar in intent to the counterexample objection, but phrased differently.
How can you respond to the objection? You have three options:
· Counterattack: Attack the arguments against your premise.
· Reformulate: Reword your original premises so they avoid the objection but still lead to your conclusion.
· Change strategy: Trash your argument and try another approach.
On the counterattack option, you’d maintain that the arguments against your premise either are invalid or else have false premises. Here you might claim that stealing is wrong in this hypothetical case. This would be biting the bullet – taking a stand that seems to go against common sense in order to defend your theory. Here you’d claim that it’s wrong to steal to keep your family from starving; this is a difficult bullet to bite.
On the reformulate option, you’d rephrase premise 1 to avoid the objection but still lead to your conclusion. You might add the italicized qualification: “No dishonest act that isn’t needed to avoid disaster is right.” You’d have to explain what “avoid disaster” here means and you’d have to add another premise that says “Offering the bribe isn’t needed to avoid disaster.” Then you’d look for further objections to the revised argument.
On the change strategy option, you’d trash your original argument and try another approach. You might, for example, argue that offering the bribe is right (or wrong) because it’s legal (or illegal), or accords with (or violates) the self-interest of the agent, or maximizes (or doesn’t) the long-term interests of everyone affected by the action. Then, again, you’d have to ask whether there are objections to your new argument.
As you refine your reasoning, it’s helpful to imagine a little debate going on. First present your argument to yourself. Then pretend to be your opponent and try to attack the argument. You might even enlist your friends to come up with objections; that’s what professional philosophers do. Then imagine yourself trying to reply to your opponent. Then pretend to be your opponent and try to attack your reply. Repeat the process until you’re content with the position you’re defending and the argumentation behind it.
4.4a Exercise
Give a valid argument with plausible premises for or against these statements. For this exercise, you needn’t believe these premises, but you have to regard them as plausible. Don’t forget what you learned in Chapter 3 (“Meaning and Definitions”) about the need to understand what a statement means before you defend or attack it. 0072
Any act is right if and only if it’s in the agent’s self-interest. (ethical egoism)
· If ethical egoism is true, then it would be right for Jones to torture and kill you if this were in Jones’s self-interest.
· It wouldn’t be right for Jones to torture and kill you if this were in Jones’s self-interest.
· ∴ Ethical egoism isn’t true.
1. Offering the bribe is in the agent’s self-interest.
2. Every act is right if and only if it’s legal.
3. All acts that maximize good consequences are right.
4. Offering the bribe maximizes the long-term interests of everyone concerned.
5. Offering the bribe is a dishonest act.
6. Some wrong actions are errors made in good faith.
7. No error made in good faith is blameworthy.
8. All socially useful acts are right.
9. No acts of punishing the innocent are right.
10.The belief that there is a God is unnecessary to explain our experience.
11.All beliefs unnecessary to explain our experience ought to be rejected.
12.All beliefs that give practical life benefits are pragmatically justifiable.
13.The idea of a perfect circle is a human concept.
14.The idea of a perfect circle doesn’t derive from sense experience.
15.All ideas gained in our earthly existence derive from sense experience.
[I took many examples from §2.3a. The English arguments in this book are a rich source of further problems for this exercise.]
4.5 Analyzing arguments
To get better at analyzing arguments, get into the habit of sketching a premise–conclusion version of arguments that you read or hear. Often the arguments will be as simple as a modus tollens (“If A then B, not-B, therefore not A”); but sometimes they’ll get more complicated. It’s important to listen and read carefully, with the aim of getting at the heart of the reasoning.
Here are four steps that you may find helpful in analyzing arguments in things you read. The steps are especially useful when you write an essay on an author’s reasoning; but you also can use them to critique your own writing. The steps assume that the passage contains reasoning (and not just description).
1. Formulate the argument in English. Identify and write out the premises and conclusion. Aim for a valid argument expressed clearly and directly. Use the principle of charity: interpret unclear reasoning in the way that gives the best argument. 0073
2. Supply implicit premises where needed, avoid emotional terms, and phrase similar ideas in similar words. This step can be difficult if the author’s argument is unclear.
3. Translate into some logical system and test for validity. If the argument is invalid, you might try step 1 again with a different formulation. If you can’t get a valid argument, you can skip the next two steps.
4. Identify difficulties. Star controversial premises. Underline obscure or ambiguous terms; explain what you think the author means by these.
5. Appraise the premises. Try to decide if the premises are true. Look for informal fallacies, especially circularity and ambiguity. Give further arguments (your own or the author’s) for or against the premises.
Let’s try this on a famous passage from David Hume:
Since morals, therefore, have an influence on the actions and affections, it follows, that they cannot be deriv’d from reason; and that because reason alone, as we have already prov’d, can never have any such influence. Morals excite passions, and produce or prevent actions. Reason of itself is utterly impotent in this particular. The rules of morality, therefore, are not conclusions of our reason. No one, I believe, will deny the justness of this inference; nor is there any other means of evading it, than by denying that principle, on which it is founded. As long as it is allow’d, that reason has no influence on our passions and actions, ‘tis in vain to pretend, that morality is discover’d only by a deduction of reason. An active principle can never be founded on an inactive ….1
1 David Hume, A Treatise of Human Nature (Oxford: Clarendon Press, 1888), page 457 (Book III, Part I, Section I).
First read the passage several times. Focus on the reasoning and try to put it into words; it usually takes several tries to get a clear argument. Here our analysis might look like this:
· All moral judgments influence our actions and feelings.
· Nothing from reason influences our actions and feelings.
· ∴ No moral judgments are from reason.
Next translate into some logical system and test for validity. Here we could use either syllogistic or quantificational logic:
· all M is I
· no R is I
· ∴ no M is R
· (x)(Mx ⊃ Ix)
· ∼(∃x)(Rx • Ix)
· ∴ ∼(∃x)(Mx • Rx)
The argument tests out valid in either case.
Next identify difficulties. Star controversial premises and underline obscure or ambiguous terms:
· * All moral judgments influence our actions and feelings.
· * Nothing from reason influences our actions and feelings.
· ∴ No moral judgments are from reason. 0074
Try to figure out what Hume meant by these underlined words. By “reason,” Hume seems to mean “the discovery of truth or falsehood.” Thus we can rephrase his argument as follows:
· * All moral judgments influence our actions and feelings.
· * No discovery of truth or falsehood influences our actions and feelings.
· ∴ No moral judgments are a discovery of truth or falsehood.
“Influences” also is tricky. “X influences Y” could have either of two meanings:
· “X independently of our desires influences Y.”
· “X when combined with our desires influences Y.”
Finally, appraise the premises. If we take “influences” in the first sense, then there’s a problem with premise 1, which would then mean “All moral judgments, independently of our desires, influence our actions and feelings.” This seems false, since there are people who accept moral judgments but have no desire or motivation to follow them; the actions and feelings of such a person thus wouldn’t be influenced by these moral judgments. If we take “influences” in the second sense, then there’s a problem with premise 2, which would then mean “No discovery of truth or falsehood, when combined with our desires, influences our actions and feelings.” This also seems false, since the discovery of the truth that this flame would burn our finger, combined with our desire not to get burned, surely influences our actions and desires. Hume’s argument is plausible because “influences” is ambiguous. Depending on how we take this term, one premise or the other becomes false or doubtful. So Hume’s argument is flawed.
Here we’ve combined formal techniques (expressing an argument in a logical system) with informal methods (common-sense judgments, definitions, and the fallacy of ambiguity). We’ve used these to formulate and criticize an argument on the foundations of ethics. Our criticisms, of course, might not be final. A Hume defender might attack our arguments against Hume’s premises, suggest another reading of the argument, or rephrase the premises to avoid our criticisms. But our criticisms, if clearly and logically expressed, will likely move the discussion forward. At its best, philosophical discussion involves reasoning together in a clear-headed, logical manner.
It’s important to be fair when we criticize another’s reasoning. Such criticism can be part of a common search for truth; we shouldn’t let it descend into a vain attempt to score points. In appraising the reasoning of others, we should follow the same standards of fairness that we want others to follow in their appraisal of our reasoning. Distortions and other fallacies are beneath the dignity of beings, such as ourselves, who are capable of reasoning.