Just about any undamaged human is capable of understanding some kind of philosophy, but I suspect that not even 1/2 of all humans are capable of understanding many particular philosophies.
Questions: What are the problems with the above? Is it precisely worded? How many of those observations also apply to the parent-post assertion?
Only a quite limited amount is known about how knowledge is created at a hardware level.
At a higher level (epistemology -- my specialty), there only exists one viable theory of how knowledge is created: by conjecture/guessing and refutation/criticism. This trial-and-error is an evolutionary process (literally, not metaphorically).
This process of knowledge creation is universal in character. Something either can do it, or can't. It does not conveniently allow for any limits.
Your assertion about limited and varied capacity for learning is clear, but to be compelling it would need some philosophical backing, in particular it'd need a theory of how knowledge is created that it's compatible with.
I think the issue your theory attempts to address is that a lot of people are dumb. If they have universal capacity, why don't they use it? However, this issue can be answered in other ways, e.g. by discussion of creativity-supressing memes.
Which is exactly what I wanted to talk about when I read "is capable" in your previous post.
Here is something relevant I wrote, about changing emotions (raw emotions aren't memes, but ways of interpreting and reacting to them are memes. emotions can also be triggered by ideas or memes.):
http://fallibleideas.com/emotions
The basic, overall problem is that parents and educators are extremely coercive and destroy the ability of (most) children to think for themselves (to a good approximation -- again, it's possible to recover). If you'd like to discuss that more, I'd urge you to come post your thoughts or questions on this list and I will reply (HN is not a suitable forum for longer discussions):