Out of too much learning become mad.

Certainty is not biologically possible. We must learn (and teach our children) to tolerate the unpleasantness of uncertainty. Science has given us the language and tools of probabilities. We have methods for analyzing and ranking opinion according to their likelihood of correctness. That is enough.

Properly conducted scientific studies . . . give us a pretty good idea of when something is likely to be correct. To me, pretty good is a linguistic statistic that falls somewhere in between more likely than not and beyond a reasonable doubt, et avoides the pitfalls arising from the belief in complete objectivity.

Good science requires distinguishing between "felt knowledge" and knowledge arising out of testable observations. "I am sure" is a mental sensation, not a testable conclusion. Put hunches, gut feelings, and intuitions into the suggestion box. Let empiric methods shake out the good from bad suggestions.

Employment, which Galen calls 'Nature's Physician,' is so essential to human happiness that indolence is justly considered as the mother of misery.

No one seriously doubts Socrates' maxim: The unexamined life isn't worth living. Self-assessment and attempts at self-improvement are essential aspects of "the good life." Yes, we should engage in ruthless self-reflection and harsh scrutiny, but we should simultaneously acknowledge that such introspection will, at best, only result in a partial view of our minds at work. Complete objectivity is not an option.

Certainty and similar states of ‘knowing what we know’ arise out of involuntary brain mechanisms that, like love or anger, function independently of reason.