11.4: Inconsistency

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We will discuss issues involving inconsistency at length in Chapter 19. For now, it is enough to recognize that the key point is that when some person (or group) is inconsistent, at least one of the things they say must be false.

People are rarely blatantly inconsistent. We don’t often say something in one breath and then say the exact opposite in the next. But people do sometimes say one thing in one setting and then deny it in another. Politicians, for example, often tell different audiences what they believe the audiences want to hear, but all of us are susceptible to the temptation to do this.

People also sometimes promise to do several things that cannot all be done together. For example, someone running for office may promise to cut taxes, keep Social Security and Medicare spending at their current levels, and beef up defense. It is unlikely that all three things can be done at once.

Organizations can also send inconsistent messages. For example, one member of a large organization may make an announcement in a way that allows other members to maintain “deniability” (i.e., that allows them to avoid taking responsibility for it).

To test your understanding, say what is wrong with the following argument:

“Well, I agree that your argument is deductively valid and that all of its premises are true. But I still think that its conclusion is false, and who are you to say I’m wrong?”