While reading the introduction of The Cambridge Companion to Merleau-Ponty (2005), I was reminded of how annoyed I get when I read criticisms that use such buzzwords as 'the subject,' 'subjectivity,' 'subjectivism,' and so forth. I never quite understand the criticisms because the notions the writers/philosophers are using are not clear.
I will attempt to make it more clear, if only for myself. Assume that by 'subject,' one means either the human mind/brain or the embodied human being. Next, assume that 'objects' are either phenomenal experiences, real things in the world, representations in the brain, or whatever you would like.
The way I have seen the basic philosophical criticism go against these concepts is to deny the distinction. Quite often, the distinction is denied using either an ad hominem or question-begging strategy. Regarding the first, the counter-argument goes like this: The distinction between subject and object is a kind of dualism, and dualisms are (morally? aesthetically?) bad, so the distinction is a bad distinction. Regarding the second, the question-begging strategy, the distinction is incoherent because a human subject cannot be separated (physically? conceptually?) from its world (i.e. its environment? the world as phenomenally perceived? what?).
I do not care very much for or about the distinction but these arguments do not seem very sound. I do not understand why proposing a conceptual distinction between the mind/brain and the world or any two objects is intrinsically otiose. Some reason for that would have to be given. Regarding the question-begging strategy, the claim of the impossibility of separation between the mind/brain or the embodied person and the world (conceived of in whatever way) is false at least at the conceptual level because--hey, lookit--I just did it. This latter criticism has as much legs as this claim: It's incoherent to speak of the circulatory system and the body (or anything else, for that matter) because the circulatory system cannot be separated from the body (or anything). Strictly speaking, in terms of human biology, it is true that the circulatory system cannot be separated from the body. But that does not mean that a person, say a scientist or biologist, could not conceptualize certain parts of the body as systems, one among them being the circulatory system, and then proceed to study it and investigate it how it works. In fact, why couldn't the same go for a kind of distinction like subject and object?
Again, I reiterate that I don't care very much about this distinction but if one wants to object to it, one should probably object to it on the grounds that it might not be prove to be a useful distinction. That is to say, by distinguishing a subject and object, not much interesting philosophical or scientific work would result. Of course, this is an empirical claim, and it would just have to be determined in terms of the work that has been done, to see if it has been fruitful, the work that is being done, and perhaps some speculation on work that will be done. I reiterate, though, that's just an empirical matter.