Holism has now evolved from a formerly minority position into a sort of universally accepted cracker barrel wisdom, good for scoring easy points on fossilized and oppressive reactionary patriarchs who are supposedly naive enough to miss the way in which “everything is connected.” The problem is that this is an idea once but no longer liberating. Ideas have lifespans just like humans, and just like humans they can fall into a robotic decadence. My wager, as Badiou would put it, is that interconnectivity is a spent force, and that the intellectual theme of our time will be the recovery of a more robust and weirder model of autonomous individual things.
My first reaction to this was, "liberating" is not the first criterion by which I evaluate assertions. But I always question my first reactions.
There is a real sense in which formerly daring positions become substitutes for thinking. It is much, much harder than one thinks to escape from this. The feeling of "scoring easy points" seems to give validation, for defeating an opponent (or at least, in one's own opinion, taking them down a notch) is a fairly satisfying simulacrum of being right, and all the better if the opponent is one of the establishment.
My own way (certainly not foolproof) of navigating this danger is roughly threefold. Each of these modes carries its own risks.
First, I read widely, from no single school. I know I risk eclecticism in this way; a more grave danger is a kind of scatteredness or shallowness, a dilettantism. I'm not too afraid of this because I consider philosophy a matter of life and death, but it is true that one can't study everything.
Second, I avoid in-crowds where I can. I value friendship above most other goods and even think that the question of friendship is one of the few perennial philosophical matters; but I cultivate an allergy to the subtle allure of relationships in which mutual interest in the truth is eclipsed by a creeping disdain for all those poor benighted other sods who just don't get it. The risk here is a certain loneliness and (again, more dangerous) a chance of being broad-minded-to-a-fault.
Lastly, in those positions that rub me the wrong way, I try to find these in their strongest form. (This is at least half of why I am drawn to Badiou, for instance). This is of course a venerable technique of keeping oneself honest, and I have to admit I think it would do a few contemporary debates a world of good; but it too carries a danger, of remaining in polemical mode too long and failing to articulate a position of one's own.
I'm sure I succumb to all of these in different degrees. What I don't do is look for the cutting edge.
As for Holism, I consider Harman one of the strong points in the case against it. His strength does not lie in his characterization of it as no-longer-liberating. (And of course this is hardly the main thrust of his critique.) He's certainly right that it has become, in some circles, a default position. (On the other hand, there is also a case to be made that reductionism remains the ideological default mode of western culture.) Which position currently holds the attention of the doxa, in whatever circles, is not really the main question. The challenge is to formulate whatever position you hold in a manner that thinks. It is always worth asking oneself if one is scoring easy points. But that is because philosophy is above all a spiritual discipline, not just the construction of arguments.