Natural numbers need not be in scope of intuition. Imagine a diffuse intelligence formed in a fluid (such a thing is at least imaginable), it has no fingers, it recognises no individual things, not even itself, it has no intuition of the natural numbers. If this being makes statement on arithmetic, like 1+1=2, according to you this statement is not "meaningfully true". Yet it is true, and this being has derived it from (abstract) thought. So what is "meaningfully true"?
You prove his point with your fluid example. Integers have _everything_ to do with our world. If we lived in a fluid world, then the mathematics of that world will not have integers.
Perhaps my point is misunderstood here: it is that if we think of mathematical truth as being based on intuition, then since what can be intuited depends on the species, on the society, even on the individual (99% of what was intuitive to Grothendieck is completely beyond me), then mathematical truth becomes relative. I say no, 1+1=2 universally, whether it is intuitive to you or not.
