The liberal tradition has always understood the unit of human behaviour as the individual; the socialist tradition as some scale of the social. Today we must insist that the unit of human activity is communicative, and for the nonce might be described as community.
In Hardt and Negri this appears as irreducile difference: this is one of the grounds for the communicative, as its absence is for the collapse of communication (see Allen Cameron's and my joint paper in Warren Buckland's forthcoming collection on complex narratives). Elsewhere it will be vital to ground the communicative in a prior ontology: mediation
As heisenberg argues, there's every reason to expect a third leg to the tripod.