History of Philosophy as a Source of Data for Psychology
I've recently become intrigued by the idea of the history of philosophy as a source of data for psychology. What variety of opinion, across cultures and centuries! Surely this says something about the human mind.
In Do Things Look Flat? I examined the course of philosophical variation in the opinion that visual appearances show the kind of shape and size distortions one sees in photographs (e.g., obliquely-viewed coins looking elliptical; distant things looking very much smaller than nearby ones). In Why Did We Think We Dreamed in Black and White? I looked (a little bit) at the history of philosophical opinion about the coloration of dreams. In both essays, I suggested that what people found to be "common sense", and what was endorsed by the most reflective philosophers and psychologists (not different people, generally, before the late 19th century), reflected culturally variable metaphors for aspects of the mind -- metaphors for visual experience and dream experience, respectively.
This variability, I think, to some extent undermines the credibility of what ordinary folk and philosophers now say about visual experience and dreams, since it raises the suspicion that this, too, is grounded in culturally contingent metaphors. We should be very wary of testimonial evidence by consciousness researchers or their subjects regarding the nature of their visual experience or dream experience.
Cultural variation in philosophy gives us a window into the variability of "common sense" and rational opinion -- somewhat like the variability cultural anthropology provides, but with a different and more public set of data, focused more deeply and exclusively, and often more carefully and with greater nuance, on ethics, metaphysics, mind, and other topics of philosophical interest. To the extent psychology analyzes the variability and sources of common sense intuitions (as in developmental psychology) or relies upon the intuitive judgments of researchers and subjects (as in consciousness studies), a sense of the relative cultural stability of those intuitions may be illuminating.
It's too easy to suppose that what we find intuitive is universally so -- or, conversely, that intuitive judgments (e.g., about ethics) vary so radically between cultures that we can find nothing in common between them. The history of philosophy provides crucial data for assessing such suppositions.
Of key importance in such an enterprise are philosophical traditions -- Asian traditions especially -- with a robust written philosophical literature and minimal Western influence.