“Strong” cognitive relativism, as Appiah puts it, is the theory that different conceptual schemes can have different truths that are equally legitimate but mutually exclusive. Section 9.6 seeks to disprove this theory. Appiah does this by introducing two hypothetical scenarios. The first scenario relies upon the assumption that a perfect translation of a sentence from one language with its own conceptual scheme leaves us with an equivalent sentence in a new language with its own conceptual scheme, taking into account the different conceptual schemes that each language carries. If cognitive relativism was true in this scenario, then there would have to exist a sentence in one of the languages that was both true and false at the same time. The second scenario rests upon an entirely different definition of perfect translation; that a perfect translation between two languages is a sentence that has the same meaning relative to only one of the conceptual schemes. This makes cognitive relativism impossible as well, because it shows that truth is not always related to a conceptual scheme.
The best way to get people to care about truth when they speak or write is to show them the power that it has. This starts at caring about truth when listening or reading. Knowledge and language is power, and, hopefully, people have enough empathy to see that when they spread “untruths” or bullshit, they take away power and the right to reason from other people. However, it may be a little idealistic to rely upon empathy to keep people interested in the truth, so I raise the following. Reason is one of humanity’s most powerful tools. When you take away reason from other people by disregarding the truth when reading and writing, those people become dangerous because they are misinformed. They develop the world in the wrong direction, because what is true to them is not “the Truth”.