The line of demarcation between natural and artificial selection seems to become blurred if one views intelligence as a product of the mind which in turn was developed by natural selection. This point in itself is highly debatable and no doubt some of you will disagree entirely. Nevertheless, let us venture down Dennett's rabbit hole. Cutting to the chase, it does open the door for everything cultural, political, and economic to be explained in the framework of the "Darwinian Algorithm". The 19th century politician did it for national competition in the West and imperialism in the Third World, the 19th century historian did it for cultural transmission, and Margaret Thatcher did it for economics. The algorithm can be applied anywhere because of its unique and ingenious construction allows it to explain anything, (although this does not necessarily mean the explanation is correct, and Dennett even allows for an imaginary super-algorithm being produced someday that does the task even more efficiently.) The point is, it can potentially be applied anywhere. But the question is where it is most usefully applied.
Now I do hope I was not misunderstood in this "ought question". I was not raising an ethical question. That would have been very dull of me. More useful is the question of where the framework is of most use. If every nook and cranny of the living world can be explained along the lines of natural selection, that is all and well. However, an all encompassing theory has a tendency to get a little stale. If the theory potentially explains everything social scientists can all retire, unless they'd like to devote their careers to filling in the details. If so, I eagerly anticipate the doctoral thesis on how does Darwinian theory guides the ability of Midwestern American housewives to make chocolate chip cookies. However, one suspects it is rather inefficient to spend our lives explaining everything. Rather, it is worthwhile to focus on things that need to be explained. In the face of an all-encompassing theory, the fact seems self evident. Therefore, a more pragmatic question seems to be, how does it aid us in pursuing our respective topics? Is, for instance, the transmission of language and culture any better understood by cramming what we now into a Darwinian framework? To a significant degree that would justify a dissertation on the subject? (which, sadly, has already been written more than once) How is any particular topic more greatly elucidated by viewing it through such a lens? That is the question we must ask ourselves. We must selfishly ask whether thinking about it that way profits us and enhances our perspective, in the same way historians today consider the usages of a 'Gender lens' or a 'Marxist lens' when writing their histories. All these algorithms or frameworks belong to what is commonly called the 'methodological toolbox' from which they draw a perspective when it is found useful to the purpose.
Where is the 'Darwinian tool' most useful and best suited? The immediate answer seems to be the obvious one - the study of the evolution of species. Alternately, in the study of human activity from Capitalism and Freedom to Mein Kampf, social and economic theory has been written taking from quasi 'Darwinist' perspectives. Yet these writings deal with topics vastly different from those with which Darwin was concerned. Nor would Darwin have necessarily agreed with how his theory was applied. Not to dismiss the many ideas in the social sciences that could not have been generated without Darwin, many of these explanations of culture seem to be an intellectual exercise at best, and at the worst, a blatant subversion of Darwin's principles. There are many ways Darwin has influenced the social sciences, but his algorithm seems to have made tangible progress seems to have been made in the realm of biology. I cannot even begin to imagine how long that list may be. A lot of quasi-social darwinist prattlings, on the other hand, have turned out to be a highly decorative waste of time. I say this as delicately as I can, with many notable exceptions in mind, as well as bearing in mind the army of scholars who would take offence to such a sweeping remark and seek hang me from a lampost. Nevertheless, if a line of demarcation cannot be clearly made because Darwin's algorithm can be deployed everywhere, to explain even the products of the human mind, perhaps a line of demarcation can at least be drawn pragmatically and opportunistically, like a tool drawn from a toolbox, it is best suited to tackling certain kinds of jobs.