“It is clear that there is no classification of the Universe that is not arbitrary and full of conjectures. The reason for this is very simple: we do not know what thing the universe is.”
There’s no encyclopaedia which can contain all possible facts about any situation. You may have good heuristics and terrific search algorithms, but when you’re up against an uncategorisable domain of infinite extent, you’re surely still going to have problems.
Aren’t they right to emphasise the potential value of introspection? Isn’t it the case that introspection is our only source of infallible information? Most of the things we perceive are subject to error and delusion, but we can’t, for example, be wrong about the fact that we are feeling pain, can we? That seems interesting to me. Our impressions of the outside world come to us through a chain of cause and effect, and at any stage errors or misinterpretations can creep in; but because introspection is direct, there’s no space for error to occur. You could well say it’s our only source of certain knowledge – isn’t that worth pursuing a little more systematically?