Universal Claim
When a universal claim is refuted by a single case, that case is a counterexample to the universal claim. The pattern of reasoning is perfectly simple: To refute a claim that everything of a certain kind has a certain feature, we need find only one thing of that kind lacking that feature. In response to a counterexample, many people just repeat the misleading saying, “That’s the exception that proves the rule.” What most people do not realize is that “proves” originally meant “tests,” so all this saying means is that an apparent exception can be used to test a rule or a universal claim. When the exception is a true counterexample, the universal claim fails the test.
There are only two ways to defend a universal claim against a purported counterexample. Because the universal claim says that all things of a certain kind have a certain feature, (1) one can deny that the apparent counterexam- ple really is a thing of that kind, or (2) one can deny that the supposed coun- terexample really lacks that feature. For example, a defender of the claim
Is refuting an argument the same as justifying a belief that its conclusion is false? Is it the same as justifying a belief that the argument is invalid or weak? Why or why not?
