One thing that makes Agamben’s Homo Sacer so difficult to grasp is that the status of the claims is very unclear. On the one hand, you have the close analysis of this particular legal figure from ancient Rome, and on the other, you have a whole range of claimed homologies from linguistics, ontology, etc., as well as some very wide-ranging claims for the relevance of the homo sacer figure for Western politics. It would seem ridiculous to claim that the legal provisions for the homo sacer are causing all the phenomena Agamben connects to it, yet the nature of the connection is never made explicit.
Only as the series went on did he develop the conceptual tools necessary to clarify what’s going on in his argument. The relatively unremarked Sacrament of Language seems to me to be the decisive turning point, insofar as it combines the concept of “anthropogenesis” (which debuts in The Open) with the Foucauldian notion of “archeology.” The oath isn’t finally what’s in question in Agamben’s investigation — the oath serves as a crucial pointer for an archeological study that takes us back to a certain moment of anthropogenesis, namely the taking up of a certain stance toward language. It’s not about either shoring up or rejecting the oath as such, but rather trying to think a new experience of language that would “reboot” our sense of what it means to be (to be becoming) human.
If Agamben had had this structure worked out when he wrote Homo Sacer, I imagine the argument would look broadly similar — after all, he worked out the methodology as he was reflecting on what he was trying to do starting from that book. But if he were less fixated on the figure of the homo sacer as such and more thinking about the archeological level of exclusive inclusion or inclusive exclusion that creates a sub-human form of life as the necessary support for the fully human, then I assume that he would have had to be more attentive to the figure of the slave, for instance — something he in fact does in The Use of Bodies.
But it’s more than methodology that makes him “not go there,” of course — like Foucault, like Arendt, he is trying desperately to create a comprehensive account of Western political structures without being a Marxist. His seeming lionization of the “normal” Greek structure where good old zoe stays put in the household so that political bios can get down to work seems symptomatic here. It’s never about returning to the “normal” state for him, but his allergy to creating a too-Marxist-sounding analysis leaves him making claims that sure sound that way. In the end, I think this might be what leads him to so over-identify with the standpoint of the law (as Weheliye diagnoses), without really attending to what underlies the law and grants it its power — and grants us room to contest its claims.