| SSD 610 INTRODUCTION to PHILOSOPHY FALL 2010 Section G24B |
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Queensborough Community College The City University of New York Introduction to Argumentation and Logic (Dr. Kincaid - Course SS 610/630 - 3 credit hrs) Arguments are essential to the practice of philosophy. This does not mean that philosophers engage in verbal fist‑fights just for the fun of it. Philosophers make arguments; that is, they give sets of reasons or various types of evidence to support specific conclusions. Logic is that branch of philosophy which concerns itself primarily with the adequacy of different types of evidence in supporting certain conclusions, and with the structure of the arguments presented in defense of those conclusions. And while not all philosophers are logicians per se, all philosophers use arguments, and thus all philosophers need logic. Two basic rules for constructing and analyzing arguments 1. Distinguish between the premises (the reasons you are giving in the justification of an argument), and the conclusion (the statement which you are defending with premises). Example: Socrates is a human being. (Premise 1) All human beings are mortal. (Premise 2) Therefore, Socrates is mortal (Conclusion). 2. Start with reliable premises, and use specific terms and definitions consistently. Types of argument 1. Argument by Example ‑ These use examples as premises in support of a conclusion. Example: The E train typically takes 25 minutes to go from 71st Avenue to 5th Ave. The V train can go from 71st to 5th in 35 minutes. Therefore, you should take the E if you are in a hurry.
2. Argument by Analogy ‑ These use one example as a basis to support a generalization to another example. Example: The E train is faster than the V train. The E runs express in Queens, while the V is a local. Therefore, express trains are always faster than local trains
3. Argument by Authority ‑ These arguments use information supplied by others to defend a conclusion. Example The MTA says that the F train is more reliable than the E. Therefore, if you want to be somewhere on time, take the F train.
4. Cause and effect ‑ When properly constructed, these arguments establish a causal relation between the premises and the conclusion. Example: Riding the subway gives you time to read. You cannot read while driving a car. Reading makes you smarter. Therefore, people that ride the train are smarter than people who drive cars. 5. Deductive Arguments ‑ These are the only types of arguments which guarantee that the conclusion is true if the premises are true. If the argument is valid, its conclusion follows from the premises. For an argument to be sound, it must be a valid argument with all true premises. A deductive argument can be valid and not sound, but if it is sound, it must also be valid. Examples: Sound Valid Dogs are mammals. Dogs are reptiles. All mammals are warm‑blooded All reptiles are worms. All dogs are warm‑blooded All dogs are worms.
The Structure of Deductive Arguments: 1. Modus Ponens If P then Q P Therefore, Q
2. Disjunctive Syllogism P or Q Not P Therefore, Q
3. Hypothetical Syllogism If P then Q If Q then R Therefore, If P then R
4. Modus Tollens If P then Q Not Q Therefore, not P
5. Reductio Ad Absurdum To prove: A - Assume : not A From "not A" derive false implication Q Therefore, A
6. Dilemma P or Q If P then R If Q then S Therefore, R or S
Common Fallacies and How to Avoid Them
A fallacy is an error in argument. Each fallacy on the following list violates one or more of the criteria for a good argument. The two greatest errors in reasoning are: 1. Drawing conclusions from too little evidence. 2. Overlooking alternative explanations or causes. The key to avoiding both of these errors lies in increasing the number of alternative explanations and relations. In philosophy, the key to effective argumentation lies not in narrowing down the possible objections to your position. Success in philosophical argumentation depends on increasing the possible responses to the various elements in your argument, and addressing them.
A List of Some Common Fallacies
ad hominem: Attacking the reputation of a person giving an argument instead of the argument itself. ad ignorantium: Claiming that a premise is true simply on the basis that it has not been proven false. ad misericordiam: Appealing to pity as a justification (e.g. If you don't give me an "A", my dad will kill me). ad populum: Arguing that something is the right thing to do because everyone else is doing it.
affirming the consequent: A deductive fallacy of the form: If P then Q Q Therefore P An example of “affirming the consequent” might look like this: If it is raining, you will have trouble getting a cab. I am having trouble getting a cab. Therefore, it must be raining. begging the question: Using the argument conclusion as a premise (e.g. My mom is the boss, and I know this because she tells me that she is the boss.). In Latin: petitio principii. complex question: Asking a question in such a way that a person cannot disagree or agree without committing him‑ or herself to some other claim (e.g. Is your mother as ugly as she used to be?). composition: Assuming that the whole has the properties of its constituent parts (e.g. Some people in Queens are cool, so Queens must be cool). denying the antecedent: A deductive fallacy of the form: If P then Q Not P Therefore, not Q Example: If it is raining, you will have trouble getting a cab. It is not raining, Therefore you will have no trouble getting a cab. division: The assumption that each constituent part has the characteristics of the composite whole (e.g. Since Queens is cool, everybody in Queens must be cool). The opposite of composition. equivocation: Using a word in more than one way. false cause: Inferring a causal relation without supporting evidence. false dilemma: Illegitimately reducing potential options (e.g. America: Love it or Leave it). non sequitur: Literally, "does not follow." In general, a reference to an argument whose conclusions are not supported by the premises. "person who" fallacy: Illegitimately generalizing from one person to all people (e.g. I knew a guy who smoked 8 packs a day and lived to be eighty, so I figured I could smoke too) poisoning the well: Using loaded terms to disparage an argument prior to mentioning it (e.g. No intelligent person could believe that ......). post hoc, ergo propter hoc: Literally, "after this, therefore because of this." An argument which illegitimately assumes causation. provincialism: Assuming a local fact is universal. red herring: The introduction of irrelevant subjects in the attempt to divert attention away from the issue at hand. straw man: Presenting a weak version of an opposing argument so as to make it easy to refute. suppressed evidence: The presentation of incomplete evidence in support of your argument, while ignoring other evidence that contradicts your claims. weasel word: Changing the meaning of a word in mid‑argument to support your claims in response to a counter‑example.
References
Morris Cohen and Ernest Nagel. 1962. An Introduction to Logic. New York: Harcourt, Brace, and Company. Irving Copi. 1982. Introduction to Logic. New York: Macmillan Publishing Company. Annette Rottenberg. 1994. Elements of Argument. New York: St. Martins's Press. Anthony Weston. 1992. A Rulebook for Arguments. Indianapolis: Hackett Publishing Company
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