The problem of epistemic evil is raised by Rene Descartes in the fourth of his Meditations on First Philosophy. In the previous meditation he believed that he had exorcised the Evil Genius who might be systematically and comprehensively deceiving us. Descartes believes that he has proven the existence of a good God who will not permit us to be always deceived. However, in the fourth meditation he considers the question of why, if a good God will not allow us to be always deceived, he still permits us to be deceived on occasion. Intellectual darkness is a bad thing, and it seems puzzling that a good God would ever let it happen.

Descartes’s answer is that we deceive ourselves. We choose to leap to conclusions before we have acquired sufficient grounding or justification for our beliefs. If we exercised epistemic discipline, and only affirmed truths when the evidence was clearly adequate, then we would never go wrong. God is not to blame for not giving us infinite minds such as his own, so we cannot legitimately complain that our powers are limited. But even our limited powers would not lead us astray if we were to refuse to give assent to claims until the evidence was clearly sufficient. Thus, we have our own willful irrationality to blame when we are deceived.

This was a pretty good answer given Descartes’s assumptions and background knowledge. However, today, thanks to the work of cognitive scientists we have a much more thorough knowledge about how massively we deceive ourselves. It turns out, that our propensity towards irrationality is much deeper than Descartes suspected. It is not a matter of consciously misusing our will-to-believe. As researchers such as Daniel Kahneman and Amos Tversky have shown in abundance, we are virtually programmed for error. We go wrong spontaneously and without any conscious effort time and time again. Much of Kahneman and Tversky’s work consisted of classifying the foibles of human reasoning, i.e. the types of information that we consistently misuse. Instead of choosing to reason badly, it is all we can do to keep from falling into these cognitive traps.

Consider confirmation bias, the almost irresistible tendency to see evidence that confirms your beliefs while not seeing disconfirming evidence. Even if it is early morning as you read this, you probably have already believed something today on the basis of confirmation bias. So have I, in all probability. Confirmation bias is incredibly pervasive and insidious. What makes it so insidious is that we are almost always oblivious to its influence.

We are especially bad with respect to our spontaneous estimates of probabilities. Consider our amazing inability to consider base rates. Driving, as I do, in S.E. Texas, it seems to me that about half the time when somebody is tailgating me in traffic it is either somebody driving a big truck or a big SUV. My spontaneous and almost irresistible conclusion is that drivers of big trucks and big SUVs make up an inordinately large percentage of the jerky, aggressive drivers. However, you have to consider that in S.E. Texas a very significant percentage of all vehicles are big trucks or big SUVs! So, the apparently excessive representation of truck and SUV drivers among the jerks may be nothing more than a base-rate effect.

It seems then, that the problems with human reasoning are much deeper than Descartes imagined, and therefore would seem to require a much more sophisticated theodicy than the one Descartes gave. What might such a theodicy look like? Why would God permit us, seemingly, to be spontaneously inclined towards bad reasoning? As we have seen, a free-will defense would not work because so many of our errors are automatic and involve no choice. Indeed, they can be very hard to resist. To see how bad things are consider how we would try to prevent ourselves from falling into confirmation bias. We would do it by looking back over our cognitive judgments and seeing if they fell into confirmation bias or, instead, duly considered contrary evidence. The problem is that in the very selection of such instances we would probably succumb to confirmation bias! We would select those instances that reinforce our conviction of our own rationality and ignore the ones that did not! Hilary Kornblith has written an entire book on how reflection often only further deceives us.

Of course, bad reasoning is not only bad in itself, but leads to all sorts of other terrible problems, including much pain and suffering. Confirmation bias supports bigotry. The bigot sees the instances that confirm his prejudice, but ignores the ones that do not. National leaders might even go to war on the basis of ginned-up “intelligence” that told them what they wanted to hear (No!). Indeed, whole societies, including ones that once prided themselves on their scientists and scientific achievements, might start to trust mountebanks, ax-grinding ideologues, and ignorant blowhards rather than scientists (A purely hypothetical society, I assure you.). Bad reasoning either causes or supports much evil.

Maybe the argument would be that God permits us to have such strong tendencies towards irrationality so that the few triumphs of reason (e.g. general relativity, molecular genetics, symbolic logic) will stand out as all the more gloriously in comparison. Such diamonds shine all the more resplendently scattered, as they are, in the general muck. But all too often the muck covers the diamonds. The recent reported confirmation of gravity waves got scant notice in the media, easily drowned out by the accounts of Donald Trump’s latest buffoonery. Einstein may have been the glory of the human race, but for every Einstein there are a million Donald Trumps. And the really shocking thing is that if the cognitive scientists like Kahneman and Tversky are right, we each, all too often, listen to our inner Donald Trumps.