Critical Thinking by Example

Example 2.2: An argument that commits the fallacy of Irrelevant Reason

P1: Some people are worried about the fate of polar bears with the melting of the arctic ice.

C: Therefore, all polar bears are white.

Fallacy of Hasty Conclusion: An argument contains this fallacy if the premise set is insufficient to warrant the acceptance of the conclusion. The conclusion is hasty because even if the premise is acceptable it does not provide sufficient support for the conclusion. The premise does not address the question of the color of polar bears that are not in the zoo. In other words, a good argument for the conclusion would include evidence about the color of polar bears wherever polar bears are found.

Example 2.3: An argument that commits the fallacy of Hasty Conclusion P1: All the polar bears we saw at the zoo today are white. C: So, all polar bears are white.

Fallacy of Problematic Premise: An argument contains this fallacy if the premise set contains a premise that cannot be granted (accepted by the audience) without further support. Notice that with example 2.4 the premise is relevant; it gives us some reason to believe the conclusion. Indeed, if the premise is true, it provides all the reason we need to believe the conclusion. To see the problem with this argument, imagine a friend of yours made this argument to you. Would you believe the premise? You probably wouldn’t without further evidence. You might ask your friend to convince you that she had not mistaken brown bears for polar bears. Perhaps your friend might convince you that this did not happen, but still this means that P1 requires more evidence for it to be acceptable. As it stands, it is an unacceptable premise.

Example 2.4: An argument that commits the fallacy of Problematic Premise P1: All the polar bears we saw at the zoo today were brown and small. C: Not all polar bears are white.