Philosophical Inquiry and Method: Analysing Arguments, Logic and Justification
What you must understand
Every question in this paper rests on your ability to take an argument apart. Identify the conclusion (the claim being defended) and the premises (the reasons offered). Distinguish deductive arguments, where the premises are meant to guarantee the conclusion, from inductive arguments, where they make it more or less probable. Learn the vocabulary of validity and soundness: a deductive argument is valid when the conclusion cannot be false if the premises are true, and sound when it is valid and its premises are actually true. Validity is about form, not truth.
Know the common fallacies: affirming the consequent, denying the antecedent, ad hominem, straw man, false dilemma, begging the question, equivocation and hasty generalisation. Understand the difference between explanation and justification, and between necessary and sufficient conditions. Be able to assess evidence: relevance, sufficiency, reliability of sources, and the difference between correlation and causation.
Traps in questions
A very common trap is a valid but unsound argument: students see correct form and assume the conclusion is true. Another is confusing an argument's truth with its persuasive force. Watch for questions asking whether a premise is necessary for a conclusion when it is only sufficient. Also beware of 'therefore' appearing before the actual conclusion, and of rhetorical questions disguised as premises.
Worked example and rule of thumb
Consider: 'If the theory is true, predictions will hold. The predictions held. So the theory is true.' This affirms the consequent and is invalid; the predictions could hold for other reasons. Rule of thumb: charitably restate the argument in numbered premises before judging it, then ask (1) is the form valid? (2) are the premises acceptable? Only then assess the conclusion.