Here 'foundation' is taken in the sense: What is the intellectual or emotional basis, starting point, axiom system or set of assumptions used for a certain science, ideology, religion or philosophy?

The best answers in most cases, at least, are these:

1. The emotional foundation and the intellectual foundation of almost anything for the human mind are two quite different things that tend to be not logically related - what you want or feel is one thing; what the facts and rational explanations are is usually something quite different.

2. The intellectual foundations of almost anything for the human mind consists of guesses - abductions, surmises, presumptions, assumptions, beliefs. This does not mean these guesses are false or unsupported, but only that they are normally not certainly true, and even if true likely not all the truth about the subject, and anyway require and involve evidence.

3. It is quite an achievement for any theory that is supposed to account for anything if it is axiomatized, consistent, and not known to be false. Indeed, such theories are rare outside mathematics and physics.

4. Though there is human knowledge - as shown by technology, that works and is based on human science, which is mostly founded on guesses - empirical knowledge, especially of a theoretical kind, is fallible and usually at most adequate.