John, good to see you posting too, and Merry Christmas!
You say this:
Surely it will not be “the fact of our ignorance in this area” that “is likely to be very important to thinking about public policy in the upcoming decades”: rather it will be our increasing understanding in this area. The fact of our ignorance was, after all, around from the beginning of time up to 1953.
Our understanding of both genetics and the biological basis of behavior is proceeding rapidly, and I assume will continue to do so for some time. This has led to many extravagant claims for knowledge that we do not have, i.e., a “gene for depression.” Such claims have obvious policy relevance, and I think that subjecting such claims to rigorous scrutiny will become increasingly important in future decades, because there will likely be many more of them.
Then you ask the following:
And what does this mean: “We do not have the practical ability to understand why person X has normal psychological make-up Y based on analysis of his or her genome”? Do you mean to say this is a thing we metaphysically cannot understand? What is the evidence for that? The name Auguste Comte mean anything?
I know of no metaphysical reason (that I am certain is true) for why we could not ultimately understand this scientifically. We don’t understand it yet, though.
Comte is a great illustration of several kinds of errors, many of which center on unfounded claims to knowledge. You link to one example of this: his claim that we could never know the chemical composition of stars. But Comte is usually thought of as the founder of sociology: a discipline that he saw as scientifically modeling human social organization based on mathematical laws (per a recent set of Corner exchanges, Hari Seldon anyone?). He and Saint-Simon were called out by Hayek as key intellectual figures in building belief in the current (not possible at some future date) capacity to predict and therefore plan society. A key intellectual task of Hayek, Popper and the other mid-20th century libertarian thinkers was to point out the pseudo-scientific nature of these claims.
It may be that someday we will be able to use knowledge of the genome to predict human social behavior sufficiently to rationally plan our political economy, but we are not there yet. We should rigorously scrutinize claims of the reduction of non-pathological human mental states to scientific phenomena, in part because of the potentially profound political implications of such findings. More precisely, all scientific claims should be subjected to rigorous scrutiny, but we should challenge the sloppy popularization of such claims unless and until they are really scientifically validated, because any such popularization may tend to create an unfounded intellectual climate hospitable to the erosion of political and economic freedom.