Several lines of reasoning have been proposed to show the incompatibility of content externalism with justification internalism. In this paper I examine two such lines of reasoning, which both rely on the general idea that since content externalism is incompatible with certain aspects of the alleged privileged character of self-knowledge, it would tend to undermine justification internalism as well. I shall argue that both lines of reasoning, as they stand, lack plausibility, though the core idea of the second line can (...) be reconstructed into a new argument which shows considerable promise. In particular, relying upon the reliability constraint on knowledge, I shall argue that the so-called ‘two-concept’ version of content externalism is incompatible with ‘the transparency of sameness of content’, and thereby would also undermine justification internalism. (shrink)