Philosophical Thinking

1. Philosophical Thinking ITP. Chapter 2

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

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

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

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

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

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

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

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

10. Post Hoc Fallacy • “Because of this, that. • 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! • One cannot always assume a direct cause-effect relation between two contiguous events.

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

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

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

14. Hypothesis contrary to fact • 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. • A claim about a hypothetical future cannot be proven.

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

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

17. False Conversion • 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.

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

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

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

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

22. Hasty Generalization • 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. • General claims from few examples are dubious, not marvy.

23. False Analogy • 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. • An analogy may not usefully shed light on the issue: it may be irrelevant or illegitimate—not marvy.

24. Equivocation • 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.

25. Contradictory Premises • 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.

26. 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. • Pathetic appeals can fail to address the issue

27. Composition • 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.

28. Division • 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.

29. Poisoning the Well • 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. • Shifting attention from the merits of an argument to a negative source may not weaken the argument.

30. Ad Hominem • 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.

31. The Genetic Fallacy • 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. • 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.

32. Appeal to Authority • 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.

33. The Slippery Slope (wedge) • 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. • A first step does not necessarily imply a second.

34. 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 conclusion is hidden in the premises, but does not stand as real proof.

35. Final Points • 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.