“There are three basic problems: how a mind can know the world of nature, how it is possible for one mind to know another, and how it is possible to know the contents of our own minds without resort to observation or evidence. It is a mistake, I shall urge, to suppose that these questions can be collapsed into two, or taken into isolation.”
Source : Donald Davidson (2001). “Subjective, Intersubjective, Objective: Philosophical Essays”, p.208, Clarendon Press