Foundationalist theories of meaning, obsolete?

In general, foundationalism has been regarded as a waste of time. Postmodernism is essentially a philosophy that regards foundationalist attempts at understanding human behavior or the world as misguided.

Personally, as a Tractarian, I believe in the ontology of facts in logical space or 'state space'. It's what the logical positivists called 'objects' or 'simples' that constitute the behavior of a system. In a recent thread hereabouts, these 'simples' were called 'brute facts'.

I'm also a Platonist, which reinforces my foundationalist belief. I find it hard to believe that some premises or axioms can't be derived from a system to describe its long-term behavior.

So, what are your opinions on the matter? It seems to me that anti-foundationalism is the same as some sort of ontological solipsism, where one is only aware of their own sensory data/experience and asserts that you don't exist due to that fact.