 Goldman initially distinguished two importantly different sorts of justified beliefs—those that result from belief-independent processes and those that result from belief-dependent processes. The former are processes that take as their “input” stimuli other than beliefs; the latter are beliefs produced by processes that take as their input at least some other beliefs. So, for example, it is possible that we have evolved in such a way that when prompted with certain sensory input we immediately and unreflectively reach conclusions about external objects. And we may live in a world in which beliefs about the external world produced in this way are usually true (or would usually be true if enough of them were generated). Such beliefs will be justified by virtue of being the product of reliable belief-independent processes. This is basically the “base clause” of the reliabilist’s analysis, a principle of foundational or noninferential justification: if a belief is the product of a reliable belief-independent process, then it is justified. Reliabilists generally add to this a condition requiring, in effect, that there be no defeaters available to the subject—e.g., no good reason or justification to think that the belief is false, unreliable or untrustworthy. (Specifying the needed “no defeater” condition in the base clause without using epistemic terms like ‘justification’ and ‘reason’ is a nontrivial matter. Goldman (1979) proposes adding the condition that there be no reliable belief-withholding process available to the subject.) These foundational beliefs can in turn be taken as input for reliable belief-dependent processes in order to generate still more justified beliefs. A belief-dependent process is “conditionally” reliable if its output beliefs are usually (or would usually) be true if the relevant input beliefs are true. The output beliefs of conditionally reliable belief-dependent processes are justified, provided that the input beliefs are justified. This is basically the “recursive clause” of the reliabilist’s analysis, a principle of nonfoundational or inferential justification: if a belief is the output of a conditionally reliable belief-dependent process, and the input beliefs are justified, then (absent defeaters) the output belief is justified.