 Next, let us consider why reliabilism is an externalist theory. Reliabilism says that the justification of one’s beliefs is a function of the reliability of one’s belief sources such as memorial, perceptual and introspective states and processes. Even if the operations of the sources are mental states, their reliability is not itself be a mental state. Therefore, reliabilists reject mentalist internalism. Moreover, insofar as the reliability of one’s belief sources is not itself recognizable by means of reflection, how could reflection enable us to recognize when such justification  obtains?[38]  Reliabilists who take there to be no good answer to this question also reject access  internalism.[39]