That motivations fail to agglomerate is exhibited in the most striking logical feature of internalism (and of its cruder relative, instrumentalism), namely, that one’s bottom-line desires and projects are incorrigible.
You want what you want, and someone who insists that you are wrong to do so, when mistakes about such things as how to get what you want are not at issue, is just blufﬁng.
Subjective motivations can change, in all manner of ways, but they cannot be corrected, and this means that nothing could count as the rational investigation, on the part of such a creature, as to whether its bottom-line guidelines and priorities were correct. Since the creatures do not correct their own motivations, the design strategy is reasonable only if they do not need to; in other words, only if, for the most part, the designer can equip them with motivations (or ensure that they pick up motivations from their surroundings) that will not need correction. That in turn is feasible only if the designer can anticipate the practical problems his creatures will face, and only if the guidelines his creature would need to negotiate them are sufﬁciently compact to be stored and accessed. Given plausible cognitive constraints on processing, memory, and so on, that in turn requires that the environment the creature is anticipated to face be both stable and simple.
Coloring in the line drawing, we see that [Bernard] Williams’s alethic state of nature is something on the order of a tourist-brochure version of a village in the hills of Provence, where life goes on as it has since time immemorial. The villagers work their plots of land, growing the same grains and vegetables they always have; they herd their sheep and goats; they bake rustic bread and knit rustic clothes; they hunt rabbits and deer; they build houses out of the local stone; they marry and raise children; when they get old, they sit outside the village pub and drink pastis; they play boules in the park; eventually, they die, and are buried in the cemetery behind the church. The internalist design solution is satisfactory for this form of life. The designer knows that his peasants will have to work the ﬁelds, so when it comes time to own a ﬁeld and work it, they come to have a desire to do so. They need to be made to reproduce, and thus are built so that, when they get old enough, they will want to have children, or anyway want to do things that as a predictable side effect produce children. Not all of a subjective motivational set need be hardwired, of course; a disposition to mimic others, and to learn and adopt one’s elders’ thick ethical concepts, will keep the games of boules going and the pastis ﬂowing. Because life in the mythical village never changes, there is no need to delegate to the peasants themselves the task of investigating what their motivations ought to be, and no need to equip them to correct their motivations; thus, there is no need to complicate their cognitive or normative systems with the gadgetry that would take.
Analytic philosophy has done something that is quite peculiar: instead of making sense of humanity, we have been philosophizing for the inhabitants of a romantic fantasy of traditional peasant life.
Instrumentalist (or “Humean”) theories of practical reasoning are how philosophers talk through the strategy of hardwiring designated objectives into an organism, so that it can execute a life plan suitable to a stable environment. Your environment is no longer stable enough for relying on desires to be a decent strategy. Instrumentalists (“Humeans”) have a view of practical rationality suitable for a cruder, simpler species.
The Great Endarkenment, ‘D’où venons-nous . . . Que sommes nous . . . Où allons-nous?’