But then there's Manne's view, described here, according to which:
people may know full well that those they treat in brutally degrading and inhuman ways are fellow human beings, underneath a more or less thin veneer of false consciousness.One question this raises is what exactly it means to "know full well" that someone is a human being. Gaita warns explicitly that he makes no claim to know "what it is to be fully human." Manne talks about various capabilities, such as rationality, agency, and judgement, that human beings are recognized as having, but she doesn't talk about meaning in the way that Gaita does. In other words, I think it would be possible to know full well that someone is human, in Manne's sense, while still failing to see that person's full humanity, in Gaita's. They aren't using the same concepts.
A second question raised by the quotation from Manne above is about what difference is made by the veneer of false consciousness to which she refers. To know that someone is human, but to do so under a veneer of false consciousness, is not to know fully that that person is human after all. The false consciousness undermines the belief involved in knowledge (conceived of as something like justified, true belief). Racists both do and do not believe that their targets are human beings, which is at least part of how they fail to see their full humanity: they see parts of it, perhaps including the capabilities Manne identifies, or perhaps even all of it, but only to a limited degree. They might, for instance, recognize the full range of emotions, but deny that they have the same depth in some people as in others. And part of seeing the full depth of another's emotions is caring about them, taking them seriously.
The racists' lack of seriousness about selected others comes out in humor. It is notable that in Paul Bloom's review of Manne's book (and others) he describes mockery of black soccer players and of Jews in Nazi Germany as if it were merely sadism. In reference to the taunting of soccer players he says that "the whole point of [the taunters'] behavior is to disorient and humiliate." Surely, though, part of the point is to have a laugh at the players' expense. We may not find it funny, but the racists who mock and taunt clearly do. They are cruel partly for the sake of laughter and they laugh, partly, in order to encourage further cruelty. The lack of seriousness feeds on itself.
[You can see how old this post's origins are in this paragraph.] The same lack of seriousness is evident, it seems to me, in chants of "Lock her up!" and "Build the wall!" No doubt some people really want these things to happen, while for others it is simply fun to join in the shouting (to "own the libs", for instance). But I suspect for most there is no question of whether the idea in question is seriously meant or not. It is part serious, part joke, and there is no interest at all in thinking about it any more than this. To the extent that it is meant, for many it is probably something they want more as a joke than anything else. That is, it would be funny to them if Hillary Clinton were really locked up. They don't seriously, soberly believe that criminal justice requires it. They also, of course, don't really care about justice much at all, at least not while they are in chanting mode.