13.6: Review of Major Points

Inductive arguments are more common than deductive arguments, and they are more difficult to analyze, but logical reasoners need to be able to handle both kinds of argument. The quality of an inductive argument is always a matter of degree, unlike the quality of deductive arguments. With even the strongest inductive arguments there is a small probability that the conclusion is false even if the premises are true, unlike with deductively valid arguments. In this chapter we considered the value of anecdotal evidence and reviewed some of the problems with inductive arguments that appeal to the opinions of authorities. We examined several other types of inductive argumentation, but gave the most attention to generalizing from a sample. Generalizing from a sample is also called inductive generalization. To improve your chances of obtaining a representative sample, you should get a random, large, and diverse sample when you can. Arguments by analogy are attacked by finding disanalogies and by extending the analogy in unexpected directions. We introduced the problem of re-assessing the strength of an inductive argument when new information becomes available. We took a short foray into the mine field of statistics and noticed some ways people can lie with statistics. We introduced the subject of probability and learned to avoid the gambler’s fallacy, and to judge that it is always more probable that any two events will occur than that these two plus a third will occur.