When it comes to the truth, we are lappy. We insist that the world lay the truth in our laps for us, perfectly presented, with no distractions or imperfections, custom fit to our personal prejudices and habits of thought.
We take this habit of the mind for reasonableness, or common sense, or mathematical or scientific rigor (that is, we take it in the most flattering light possible), but it's none of those things. Those are just the clothes our mind wears to feel good about itself. Lappiness is one part laziness, one part obsessive-compulsive disorder, and one part self-centeredness. We expect the world to work the way we want it to, to present truths to us in prechewed form, to satisfy our irrational criteria for what counts as true (such as whether we like it, whether it makes us feel good about ourselves, whether it confirms what we already believe, whether it's easy to believe).
The world does no such thing, of course. Outside the world of theory and math, the truth never comes to us in pure, flawless form. The truths of the real world always come to us in complex mixtures, tangled, clad in imperfections and contradictions, precious metals but only in ore form, gems but only in the rough. If we focus only on the critical role of the mind, on searching for imperfections and pushing away anything that contains them, we will reject every actual truth the world has to offer us and eventually be left with nothing but those prejudices too strong and familiar and pure for us to bear to discard them.
This is one of those unpleasant paradoxes of the real world, that the critical faculty whose intent is to purify the truth will in human beings instead tend to purify their prejudices. Those who give in to this obsessive-compulsive habit of the mind tend to deal less and less with real information (too messy) and more and more in false but pure abstrations (mind versus matter, free will versus determinism, sane versus insane, conservative versus liberal, market versus government). This is how people tend to become caricatures of themselves over time, eventually seeing the world only as a dreamworld of artificial but pure categories that lend themselves to the lappy habits of the mind, reacting to other people not as who they really are but instead as how the viewer has categorized them, sleep-walking through life.
In the authentic search for the truth (rather than just its usual simulation), we do not get to begin with true a priori assumptions, nor do we get to logically deduce the truth like some kind of biological calculator. The mind is not a computer and life is not a logical syllogism. We take the processes of criticism and logic too much for granted as tools in the search for the truth. If we mechanically apply them outside their proper and limited domains, we become the man with the hammer to whom all problems look like nails. We become Procrustes again, stretching, twisting, and chopping the truth until its distorted corpse "fits" upon the bed of our minds.
The impurity, the paradoxes, the messiness and miscegenation of truth in the real world requires a very different approach. We have to start by abandoning the role of the lazy critic who waits for the truth to come to him in perfect, predigested form. On the contrary, not only must we search for the truth actively (to turn over much dirt in our search for gold, as Heraclitus put it), we must also learn to be suspicious of lappy information. The only truths that seem to fit us perfectly are those too consistent with our own prejudices to be true.
So here's an imperfect but useful logical syllogism for us all.
Delusions come easily to us, truths only with much difficulty. Therefore, if we don't have to work for it, it can't be true.