The Structure of Knowledge and the Danger of Circular Reasoning

§3.4

Because we can acquire knowledge by inference, our knowledge of some things depends on our knowledge of others. If, to return to an earlier example, we know that Natalie murdered Carl, because we know that the murderer had access to his rose garden and that only she had such access, then our knowledge that she is the murderer depends on our knowledge of these two premises. The same pattern holds for lower epistemic statuses. If it were merely probable that the killer had access to the garden, then it would be merely probable that Natalie was guilty, and the probability of her guilt would depend on that of the premises. For the sake of simplicity however, let’s ignore these other epistemic statuses for the time being and restrict our discussion to knowledge.

Our ability to use the conclusion of one argument as a premise for another leads to knowledge having a sometimes-complicated structure, in which one piece of putative knowledge can depend on an earlier piece, which depends on a still earlier one. It is important when making and evaluating arguments, to keep this structure in mind and to consider which earlier beliefs the premises depend on.