I know intelligence is not the same as moral virtue. As my mom says, IQ produced the atomic bomb. What I find, though, is that a lot of people do seem to suggest their equivalence. For example, some social scientists claim a correlation between IQ and incarceration rates.
I am pretty skeptical about classifying the mystery of a person with a psychometric number. But what if the data really do show a correlation?
In the first place, the proposition “low IQ causes crimes” seems to me to assume determinism and deny free choice of the will. Crimes are chosen, not caused.
In the second place, the slippery slope is very slippery. It was this kind of thing that led to Josef Mengele. If low intelligence really is associated with higher incarceration rates, what is to stop us from plunging headlong into controlled breeding, selecting for high intelligence?
Your mother sounds like a wise woman. And I’m with you about the mistake of reducing the mystery of the person to a psychometric number. But I think you are worrying too much.
Suppose there really is a connection between low intelligence and high rates of incarceration. This would not imply either that intelligence is a moral quality, or that determinism is true.
For consider: Temptation by itself is not sin, but a person of low intelligence may well be more exposed to certain temptations to sin than other people are. He may be more easily frustrated, he may feel that the world has cheated him, and he may envy those who can use their intelligence to make money.
Turning the coin over, a person of high intelligence will also be more exposed to certain temptations to sin – but different ones. He may be more prone to pride, he may think ordinary social norms are for stupid people -- not people like him -- and he may be clever enough to come up with ways to be dishonest that aren’t actually illegal (or that are illegal, but that aren’t so likely to get him arrested).
Since persons in each group tend to be exposed to different kinds of temptations, those in each group who do give in to temptation will tend to commit different kinds of wrongs. So a highly intelligent person may be just as likely to sin -- but less likely to sin in the particular ways that our criminal justice system is equipped to deal with.
To put the point another way, although an increase in average intelligence might change the kinds of wrongs which are most likely to be committed, it would not reduce the overall incidence of wrong.
Now as to the evil of eugenics, or controlled breeding. You are concerned about a slippery slope, but there are two different kinds of thing that might be called a slippery slope.
Sometimes a moral error puts a person on a logical conveyor belt to further moral error. For example, defenders of abortion often argue that unborn children may be killed because they lack what the defenders consider hallmarks of personhood, such as the ability to make and carry out complex plans. Notice, though, that very small born children lack these characteristics too. Consequently, the “not a person yet” defense of abortion easily morphs into a “not a person yet” defense of infanticide and toddlercide. This kind of slippery slope concern is valid.
On the other hand, the sort of slippery slope you have in mind is of a different kind, because it isn’t about moral error leading to further moral error. Your concern is that a possible truth may lead to moral error – because if the intelligence-incarceration correlation is valid, you think, eugenicists would try to find some way to make use of this fact. This kind of slippery slope concern is dubious.
Mind you, it isn’t that eugenicists wouldn’t try to find some way to make use of the fact. Of course they would. But wicked persons seek ways to make use of every fact. That is how evil works. It has to, because evil is a parasite on good, and lying is parasitic on truth. The solution is to be suspicious, not of truths, but of their employment for bad ends. Embezzlers misuse the truths of arithmetic, poisoners the truths of chemistry, but arithmetic and chemistry are not the enemy; the enemy is their abuse. Sometimes it may be necessary to anticipate such abuses and work out ahead of time how to thwart them -- that may be what you are hoping to do. But let us be friends with the truth itself.
So don’t waste your waste time trying to defend against eugenics by denying a correlation which you are inclined to believe may be true anyway. No correlation can show eugenics to be morally wholesome. Very good arguments do show it to be morally corrupt, because humans are not stuff to be manipulated.