A final epistemological doctrine for which Chisholm is particularly well-known is internalism. Chisholm characterized internalism in the following way: ‘The internalist assumes that, merely by reflecting upon his own conscious state, he can formulate a set of epistemic principles that will enable him to find out, with respect to any possible belief he has, whether he is justified in having that belief. The epistemic principles that he formulates are principles that one may come upon and apply merely by sitting in one’s armchair, so to speak, and without calling for any outside assistance. In a word, one need only consider one’s own state of mind’ [TK3: 76]. A crucial implication of this doctrine is that people whose conscious states are alike must be justified in believing the same propositions. Also present in the quoted passage is a related theme concerning the autonomy of epistemology. Chisholm held that epistemologists did not need the assistance of the empirical sciences in answering their purely epistemological questions. In advancing these doctrines, Chisholm took issue with the externalist and naturalistic theories, such as the causal theory and reliabilism, that gained favor with many epistemologists toward the end of Chisholm’s career.