Philosophical Thinking ITP. Chapter 2

Questions to Consider How is language central to the thinking process? How is language central to the thinking process? How do symbols reveal and hide the truth? How do symbols reveal and hide the truth? Are there reliable rules for reasoning? Are there reliable rules for reasoning? Must true arguments be logical? Must true arguments be logical?

Language and Discourse Meaning is conveyed by symbols. Meaning is conveyed by symbols. Semantics studies the clarity of word meanings. Semantics studies the clarity of word meanings. Truth-statements are called propositions. Truth-statements are called propositions. Propositions form arguments. Propositions form arguments. Arguments are comprised of premises that lead to conclusions. Arguments are comprised of premises that lead to conclusions.

Inductive Reasoning I Draws conclusions from specific evidence drawn from observation. Draws conclusions from specific evidence drawn from observation. Inductive conclusions are probable, but not final. Inductive conclusions are probable, but not final.

Guidelines for Reliable Induction How complete is the evidence? How complete is the evidence? How reliable is the evidence? How reliable is the evidence? How typical is the evidence? How typical is the evidence? What negative instances contradict the evidence? What negative instances contradict the evidence? What alternative theories are equally reasonable? What alternative theories are equally reasonable?

Deductive Reasoning I Valid deductions are certain and necessary. Valid deductions are certain and necessary. The premises force the conclusion. The premises force the conclusion. All humans are mortal. All humans are mortal. Socrates is a human. Socrates is a human. Socrates is a mortal. Socrates is a mortal.

Distinctions Induction Induction Probable conclusions Probable conclusions Are strong Are strong Conclusion has information not in the premises. Conclusion has information not in the premises. Deduction Deduction Conclusions necessarily follow from the premises. All necessary information is in the premises.

Fallacies Errors in logic. Errors in logic. Reflect lack of clarity or focus. Reflect lack of clarity or focus.

Fallacy of Equivocation Anyone mature enough to go to war is mature enough to vote. Anyone mature enough to go to war is mature enough to vote. Using a word in two different senses is not clear or accurate. Using a word in two different senses is not clear or accurate.

Post Hoc Fallacy “Because of this, that. “Because of this, that. Because Evelyn carried a rabbit’s foot she was lucky. Because Evelyn carried a rabbit’s foot she was lucky. We can’t take Lily to the picnic, because every time we do, it rains! We can’t take Lily to the picnic, because every time we do, it rains! One cannot always assume a direct cause- effect relation between two contiguous events. One cannot always assume a direct cause- effect relation between two contiguous events.

Fallacy of False Dilemma Either people are religious or atheists. Either people are religious or atheists. Placing people in two exclusive categories does not describe an actual state of affairs. Placing people in two exclusive categories does not describe an actual state of affairs.

Argumentum ad Ignorantum God exists because you can’t prove He doesn’t. God exists because you can’t prove He doesn’t. You cannot prove a negative. You cannot prove a negative.

Argumentum ad hominem What does he know of patriotism, he can’t speak English! What does he know of patriotism, he can’t speak English! Discrediting or attacking the person does not discredit his argument. Discrediting or attacking the person does not discredit his argument.

Hypothesis contrary to fact If dad had been rich, I’d be a successful surgeon by now. If dad had been rich, I’d be a successful surgeon by now. If Madame Curie had not left the photographic plate in the drawer, we wouldn’t know today what we know of radium. If Madame Curie had not left the photographic plate in the drawer, we wouldn’t know today what we know of radium. A claim about a hypothetical future cannot be proven. A claim about a hypothetical future cannot be proven.

Straw Man Go ahead and build your nuclear plant, I know you don’t care about the environment! Go ahead and build your nuclear plant, I know you don’t care about the environment! Misrepresenting an argument does not strengthen your argument. Misrepresenting an argument does not strengthen your argument.

False Obversion Children learn easily; therefore, adults learn with difficulty. Children learn easily; therefore, adults learn with difficulty. Misuse of contrasts can lead to assertion that a truth implies that its opposite is false. Misuse of contrasts can lead to assertion that a truth implies that its opposite is false.

False Conversion All patriots pledge the flag; therefore all who pledge the flag are patriots. All patriots pledge the flag; therefore all who pledge the flag are patriots. Switching the subject and predicate does not make a parallel truth statement. Switching the subject and predicate does not make a parallel truth statement.

Reification Science will turn us into robots. Science will turn us into robots. Personifying concepts may create an false metaphor. Personifying concepts may create an false metaphor.

Ambiguity People have equal rights. People have equal rights. Slow moose crossing. Slow moose crossing. The words may confuse the reader by offering more than one interpretation. The words may confuse the reader by offering more than one interpretation.

Death by a Thousand Qualifications Ann Onymous is the most brilliant student I have taught. Ann Onymous is the most brilliant student I have taught. The number of qualifications must be anticipated if the claim is to remain sound. The number of qualifications must be anticipated if the claim is to remain sound.

Oversimplificaton (dicto simpliciter) Taxation is unfair. Taxation is unfair. Exercise is good, therefore everybody should exercise. Exercise is good, therefore everybody should exercise. If we fail to include modal qualifiers in a claim, it is weakened, not magnif. If we fail to include modal qualifiers in a claim, it is weakened, not magnif.

Hasty Generalization My mail-order shoes do not fit—no mail- orders can be trusted. My mail-order shoes do not fit—no mail- orders can be trusted. You and I can’t speak French; therefore nobody can speak French. You and I can’t speak French; therefore nobody can speak French. General claims from few examples are dubious, not marvy. General claims from few examples are dubious, not marvy.

False Analogy If we allow Vietnam to fall to the Communists, then the rest of Southeast Asia will fall, like dominoes, to the Communists. If we allow Vietnam to fall to the Communists, then the rest of Southeast Asia will fall, like dominoes, to the Communists. Students, like surgeons, lawyers, and carpenters at work, should be allowed to look at their texts during exams. Students, like surgeons, lawyers, and carpenters at work, should be allowed to look at their texts during exams. An analogy may not usefully shed light on the issue: it may be irrelevant or illegitimate—not marvy. An analogy may not usefully shed light on the issue: it may be irrelevant or illegitimate—not marvy.

Equivocation Euthanasia means “good death” therefore all acts of euthanasia are good. Euthanasia means “good death” therefore all acts of euthanasia are good. The claim does not follow from the grounds because two meanings of the word are used. The claim does not follow from the grounds because two meanings of the word are used.

Contradictory Premises If God can do anything, then can He make a stone that is impossible to lift? If God can do anything, then can He make a stone that is impossible to lift? When the premises of the argument contradict, it is not a keen argument. When the premises of the argument contradict, it is not a keen argument.

Ad Misericordiam My qualifications for the job are that my crippled wife and I have six starving, ragged, shoeless kids; we have no beds; no heat in the house, and it is winter. My qualifications for the job are that my crippled wife and I have six starving, ragged, shoeless kids; we have no beds; no heat in the house, and it is winter. Pathetic appeals can fail to address the issue Pathetic appeals can fail to address the issue

Composition A team of five NBA stars is the best team in basketball if each is the best at his position. A team of five NBA stars is the best team in basketball if each is the best at his position. It does not follow that the properties of each member of a group can carry his properties to the group. It does not follow that the properties of each member of a group can carry his properties to the group.

Division The average family has 1.8 children, therefore I am likely to have 1.8 children. The average family has 1.8 children, therefore I am likely to have 1.8 children. The properties of a group may not (or cannot) be assigned to an individual. The properties of a group may not (or cannot) be assigned to an individual.

Poisoning the Well Equal rights for women are guaranteed in the writings of Marx and Engels—therefore equal rights for women are Communist practices. Equal rights for women are guaranteed in the writings of Marx and Engels—therefore equal rights for women are Communist practices. My opponent is a liar—you can’t believe him. My opponent is a liar—you can’t believe him. Shifting attention from the merits of an argument to a negative source may not weaken the argument. Shifting attention from the merits of an argument to a negative source may not weaken the argument.

Ad Hominem Jones has twice been convicted of clergy assault; he is not qualified to judge if prayer should be permitted in public schools. Jones has twice been convicted of clergy assault; he is not qualified to judge if prayer should be permitted in public schools. To attack the person and not his argument may weaken your argument. To attack the person and not his argument may weaken your argument.

The Genetic Fallacy Jefferson owned slaves, therefore he deserves our contempt and the ideas of the DOI are invalid. Jefferson owned slaves, therefore he deserves our contempt and the ideas of the DOI are invalid. Capital punishment arose in barbarous times; we are civilized; therefore we should discard capital punishment. Capital punishment arose in barbarous times; we are civilized; therefore we should discard capital punishment. The impeachable credentials of an individual do not negate his or her merits. The impeachable credentials of an individual do not negate his or her merits. The curious circumstances surrounding an issue need not be relevant to judging it in the present. The curious circumstances surrounding an issue need not be relevant to judging it in the present.

Appeal to Authority Al Gore got the Nobel Peace Prize for An Inconvenient Truth, therefore his claims about global warming must be a fact. Al Gore got the Nobel Peace Prize for An Inconvenient Truth, therefore his claims about global warming must be a fact. Authority is not evidence for the truth of views. Authority is not evidence for the truth of views.

The Slippery Slope (wedge) If we allow students to use all the bathrooms, we will have a return to rampant smoking in the school. If we allow students to use all the bathrooms, we will have a return to rampant smoking in the school. Handgun registration will lead to a police state. Handgun registration will lead to a police state. A first step does not necessarily imply a second. A first step does not necessarily imply a second.

Begging the Question The fact that we have not been attacked by Al Quaeda since 9/11 proves that our deterrent methods are working. The fact that we have not been attacked by Al Quaeda since 9/11 proves that our deterrent methods are working. The conclusion is hidden in the premises, but does not stand as real proof. The conclusion is hidden in the premises, but does not stand as real proof.

Final Points We all think with emotion; but it is important to balance thinking and emotion when reasoning. We all think with emotion; but it is important to balance thinking and emotion when reasoning. Clear thinking is never absolute, but the goal is to be as precise as possible. Clear thinking is never absolute, but the goal is to be as precise as possible.