 One feature that is shared by wishful thinking and confused reasoning is doxastic unreliability. These belief-forming methods commonly generate beliefs that are false rather than true. By contrast, what types of belief-forming processes commonly confer justification? They include standard perceptual processes, remembering, good reasoning, and introspection. What is shared by these processes? What they share is reliability: most of the beliefs they produce are true. (This formulation will be slightly refined later.) Thus, the central proposal made in “What Is Justified Belief” is that the justifiedness or unjustifiedness of a belief is determined by the reliability or unreliability of the process or processes that cause it. Reliability can here be understood either in a frequency sense (pertaining to what occurs in the actual world) or in a propensity sense (pertaining both to the actual-world and other possible worlds.). A belief earns the status of “justified” if it is produced by a process (or series of processes) that has a high truth-ratio. Precisely how high a truth-ratio must be in order to confer justifiedness is left vague, just as the concept of justification itself is vague. The truth-ratio threshold need not be as high as 1.0, but it must surely be greater (presumably, quite a lot greater) than .50.