9.6: Review of Major Points

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Bradley H. Dowden
California State University Sacramento

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In this chapter we examined the notion of inconsistency, which plays such an important role in judgments of improbability. We considered how one sentence can be inconsistent with another, as well as how a sentence can be self-contradictory and can be inconsistent with its presuppositions. A verbal statement can even be inconsistent with the speaker's body language or tone of voice. Finding an example that is inconsistent with a general claim of the form “All As are Bs” will serve as a counterexample that refutes this general claim. Finding a counterexample is not, however, the only way to refute a claim.

When you are given inconsistent information, you should reject some of the information to resolve the problem and achieve consistency among the remaining pieces of information. Because you also want to find the truth, you should always reject the information that is the least well supported or the most likely to be false. However, in cases where it isn't clear what to revise, you need to search for more information (and hope that in the meantime you will not have to act on the information you have). One important lesson from this discussion is that, when trying to assess a belief, you should not cover up counterevidence, and you should pay attention to the strength, or degree of certainty, with which you should hold a belief.