Why

Why are you studying philosophy with psychology? What do you want to achieve and how will you do it?

Whatever your answer, it should probably be based on some ideas about what combining the two disciplines might enable you to know that you could not otherwise know.

Maybe it is helpful to consider one potential reason.

Epistemology vs the People

Gettier’s proposed counterexamples (Gettier, 1963) are widely held to show that justified true belief isn’t sufficient for knowledge. Here is the leading philosophy encylopedia:

"as Edmund Gettier showed ... there are cases of [justified true belief] that are not cases of knowledge. [Justified true belief], therefore, is not sufficient for knowledge" (Steup & Neta, 2025)

But are Gettier’s cases genuine counterexamples? Starmans & Friedman (2012) asked non-philosophers to evaulate them and found that they did not reliably treat them as counterexamples. They conclude that:

"the lay concept of knowledge is roughly consistent with the traditional description of knowledge as justified true belief" Starmans & Friedman (2012)

Whether this matters depends on the assumptions and aims of your philosophical theory. Perhaps you aim to offer only a theoretically coherent position about how we might think. But if your view rested on truths about how all humans think, that would be a problem.

Some epistemologists do appear to make claims that about an unspecified group of people’s minds. Here is one of Warwick’s own:

"our fundamental conception of what it is to know that P is itself an explanatory conception ... we think of S's knowledge that P as something that can properly be explained by reference to what S has perceived or remembered or proved or ..." (Cassam, 2007, p. 356)

Meanwhile cross-cultural research is starting to provide tools to investigate commonalities and differences between groups of peope (Weisman et al., 2021, p. 1359). To what philosophical ends, if any, might it be valuable to know how people actually think?