On General Truths...

"All generalizations are false, including this one" / Mark Twain

I have paraphrased this into my own version which highlights what I believe is the key reason for the genious of the quote:
"There are no general Truths, but some are useful"

Obviously this quote is not a general truth (by its own definition), but even though it isn't, it is useful (implied by its own definition). This means that even if truth cannot be completely established, we can believe things are if it is useful and refer to this statement for justification.

It's not a general proof, but then again it doesn't need to be.