Epistemology (the study of knowledge) is one of the three main branches of philosophy, together with metaphysics (nature of reality), and aesthetics (nature of beauty). The study of knowledge remains one of the most dense and unresolved areas in philosophy. Some of the usual concerns of epistemology are: What is knowledge? How can knowledge be acquired? To what extent can any subject or entity be known? What are the limits of knowledge?
There are two main traditional theories as to how knowledge is obtained: either through the senses and perception (empiricism; e.g.; Locke’s “All ideas come from sensation”) or through reason (rationalism; e.g.; Descartes’ “I think therefore I am”).
There has been much movement in epistemology from the basic structure of this empiricism-rationalism debate. Both empiricism and rationalism seek common foundations upon which all other ideas are built (foundationalism). Foundationalism is problematic in several ways, two of the most basic are ‘what are these underlying foundations?’ and ‘how do these foundations connect to upstream ideas?’ Traditional/analytic philosophers propose coherentism as an alternative to foundationalism. Coherentism is the notion of it being more important that ideas make sense together and flow from one to the next than that they have immutable discernible foundations.
Continental philosophy too has a response to foundationalism and other aspects of the empiricst/rationalist debate. Gadamer enlarges the notion of epistemology, suggesting that discovering facts is just one of many edification activities; that man’s focus is self-betterment, a higher level than knowledge acquisition. Likewise Heidegger thinks that the higher-order engagement of man is beyond knowing facts and rather in understanding. Further that the circular structure of interpretation (the hermeneutic circle: acquiring new information and updating thoughts) is what makes knowledge possible. Rorty also calls for a larger, more holistic notion of epistemology that includes both conceptualization and the demonstration of practice.
Other new epistemologies also extend, reformulate and reinvigorate our understanding of epistemology and can be brought to bear on contemporary science and technology. Some of these alt.epistemologies are from the areas of social, feminist, queer, decolonial, and Eastern philosophy.