There’s a deep and fascinating question about whether we need “foundations” in our philosophical system, and if so, why and what kind.
First question: is the foundationalism primarily epistemological (foundations of knowledge) or ontological (foundations of being)?*
Second question: insofar as foundationalism implies a hierarchy, is the grounding or fundamental principle at the top of the hierarchy or at the bottom?
These two questions give us four positions:
top-down epistemological foundationalism: rationalism
bottom-up epistemological foundationalism: empiricism
top-down ontological foundationalism: theism/idealism
bottom-up ontological foundationalism: materialism
The ontological foundationalism can be reductive or non-reductive. Hence:
reductive top-down ontological foundationalism: idealism
non-reductive top-down ontological foundationalism: emanationism
reductive bottom-up ontological foundationalism: physicalism
non-reductive bottom-up ontological foundationalism: emergentism
Likewise, anti-foundationalism can also be epistemological or ontological:
epistemological anti-foundationalism: pragmatism (or: the good parts of Hegel/Peirce/Sellars)*
ontological anti-foundationalism: process ontology (or: the good parts of Spinoza/Whitehead/Deleuze)*
The main reason why I have resisted efforts to interpret me as an empiricist or materialist is that both empiricism and materialism are forms of foundationalism. Since I am an anti-foundationalist (both in epistemology and in ontology) I am as opposed to empiricism as I am to rationalism, and as opposed to materialism as I am to theism. My views might look like those of an empiricist/physicalist, but only if one insists on interpreting those views through the lens of the foundationalism that I reject.
As time permits I’ll explore the arguments for epistemological anti-foundationalism and ontological anti-foundationalism. For now I just wanted to get the conversation started.
*I’m leaving aside ethical and political versions of foundationalism and anti-foundationalism, though I think that’s where the philosophical action is really at.
** I’m only citing philosophers in the Western canon here, but Nagarjuna in the Madhyamika tradition of Tibetan Buddhism developed a consistently anti-foundationalist epistemology and ontology one and a half millennia before it was even conceived of in the West. Within the West, probably Nietzsche and Dewey would be the first consistently anti-foundationalist philosophers.