My current understanding is that there are three main schools of thought with regards to how a belief can be justified. The three main theories are:

  • Foundationalism, which argues that justified means arising through deduction from a most basic set of beliefs

  • Coherentism, which argues that justification is a property of a set of beliefs, not of individual beliefs

  • Process Reliabilism, which argues that a belief is justified if it arises from a reliable belief-forming process

I have read online that there is a natural trichotomy between Foundationalism, Coherentism, and "Infinitism". This is because of the following argument:

P1. Every belief must be justified from some other belief.

P2. Beliefs cannot be justified by self-reference or circular reasoning.

P3. Beliefs cannot be justified in an infinite chain of justification.

C. Beliefs cannot be justified.

P1 is rejected by foundationalists, P2 by coherentists, and P3 by infinitists.

What I'm having trouble understanding is, how does Process Reliabilism fit into this? Isn't Process Reliabilism basically the same as Foundationalism, as both involve individual beliefs being justified from more fundamental beliefs through some belief-forming process?

2 Answers 2


Per my understanding, process reliabilism (and externalism more generally) is a form of foundationalism. The question for the foundationalist is: how are our most basic beliefs justified if not by other beliefs? Externalists' answer is that their justification is external to the subject, and process reliabilism is one possible way to implement this idea.

Note that if the reliability of belief-forming processes was interpreted as a belief itself (e.g. one believes in the reliability of one's senses) then we'd fall back on a form of (internal) coherentism. However process reliabilism is generally assumed to be a form of externalism, the idea being that we generally trust our senses by default, without forming explicit beliefs on their reliability (although one can acquire beliefs about their lack of reliability in specific situations, such as optical illusions).

  • Thanks for your input. I think you may be right; certainly there are two versions of foundationalism (internalist and externalist) and process reliablism seems consistent with externalist foundationalism. I still suspect there is some larger distinction between foundationalism and process reliabilism, even if it is just a matter of what they consider to be most important. Commented Oct 11, 2014 at 10:52

The trichotomy between foundationalists, conherentists and infinitists is a debate about the structure of knowledge. The debate between internalists and externalists (reliabilism is a form of externalism) is about the nature of justification--What can act as the justification of my belief B? Must the justification of my belief be something internal like another belief (internalism) or can it be some other external fact, like the fact that my belief was produced by a reliable belief-forming faculty? This debate is an entirely different debate than the structure of knowledge debate in the sense that you could be a foundationalist and internalist or a foundationalist and an externalist and so on. Some of those combinations might make more or less sense than others, but I don't see how any of the possible combination of positions would be contradictory on its face. (Internalism and infinitism seem like natural partners to me, coherentism and externalism might be harder to make work). Still, I'm not an epistemologist, so maybe somebody else will come along to correct my understanding.

  • shane, thanks for your input. The way foundationalism, coherentism and process reliabilism were presented to me is that they are all explanation for what it means for a belief to be "justified"; this is distinct from the idea of "knowledge", which is something like "justified true belief" (pre-Gettier). Though, it would make sense if there were also forms of foundationalism, coherentism, and infinitism related to the structure of knowledge itself. Commented Oct 11, 2014 at 10:48
  • There is a standard distinction between internalist and externalist foundationalism I am aware, so this answer helps me put that in context. I suspect you are right that process reliabilism is fairly compatible with externalist foundationalism, although a reliabilist and a foundationalist may care about different things within that theory. Commented Oct 11, 2014 at 10:49

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