When I first began reading Lonergan I found myself puzzled by his distinction between intelligence and reason. Are they not the same thing, I asked myself? Certainly I had always considered them to be synonyms. So perplexed was I by this matter that I nearly threw up my hands in despair and walked away. Yet, sensing that there was something important here I persevered, and I'm glad that I did, for now not only do I grasp his distinction between intelligence and reason but recognize it as a fundamental contrast that reveals why so much scholarship can go so thoroughly awry, despite being the work of well-informed and even quite intelligent individuals. To illustrate please allow me to use this bizarre pseudo-history known as "mythicism."
For those unfamiliar, mythicism or the "Jesus myth theory" is the idea that Jesus of Nazareth never existed, that he was merely a mythical figure and the gospels are merely elaborations of that myth comparable with mythic cycles such as the Enuma Elish, the Osiris traditions, etc. Often various mystery religions are invoked. Now, of course a clever mind can identify all sorts of parallels between any two bodies of literature. More than fifty years ago, in his SBL presidential address, Samuel Sandmel coined a splendid term for this: parallelomania. I can also, if I want, declare by fiat that what appears at first glance to be historical material is in fact legendary. This is all quite possible, and a swift and nimble mind can make all sorts of contortions. Such gymnastics are all the work of intelligence, whose job is produce a coherent hypothesis, in this case that Jesus never existed and the gospels are myths.
Yet hypotheses are just that: hypotheses. They are ideas to be tested for their truth value, and that test is the work of reason. If intelligent aimed at coherent then reason aims at correspondence. Reason asks "Is this hypothesis warranted by the data?" Here mythicism fails dramatically. Its arguments are unsound from ground up. The supposed parallels between ancient myth and the gospels evaporate with remarkable haste. The gospels contain a level of historical specificity unlike what we find in these vaunted parallels. They ignore or the very least under-appreciate the parallels with historical and biographical literature, which are in fact much more impressive than those with mythical material. They commit the serious non sequiter of thinking that just because is like X means that it must be an example of X (which is to say, they elide the not inconsequential distinction between the words "like" and "is"), which is to say that they fail seriously to reckon with the possibility that something can be similar to myth yet not be myth. The arguments are tendentious, such that if they were applied to any other figure they would be seen as utterly ridiculous (as was demonstrated two centuries ago by Richard Whately, who wrote a satirical work in which he employed the sort of skepticism that is today operative among mythicist in order to prove that one cannot know that Napoleon Bonaparte never existed--and this whilst Napoleon was still alive!). When tested against the data one finds that might have first appeared to be an impressive edifice is little more than a castle in the sky.
So this great product of intelligence, this clever approach to explain the data, dissolves in the acid test of reason. It dissolves so spectacularly that one realizes very quickly that only the heavily biased could actually hold the position. It is in these regards it is to historical scholarship precisely what six-day creationism is to biology. Intelligence can work out many clever ideas, but these must be tested to see if they can be true given the extant data about the world. Reason is thus remarkably powerful. It is what allows us to distinguish real from unreal. Intelligence is not up to this task, precisely because intelligence's task is merely to suggest possibilities for reason to test. Many are called but few are chosen; many hypotheses are intelligent but few are reasonable. Mythicism, alas, is not one of the chosen few.