if the subject were a mere subject position within the structure, the latter would be fully closed and there would be no contingency at all … [Radical contingency is possible only] if the structure is not fully reconciled with itself, if it is inhabited by an original lack, by a radical undecidability that needs to be constantly superseded by acts of decision. There acts are, precisely, what constitute the subject, who can only exist as a will transcending the structure. Because this will has no place of constitution external to the structure but is the result of the failure of the structure to constitute itself, it can be formed only through acts of identification. If I need to identify with something it is because I do not have a full identity in the first place. These acts of identification are thinkable only as a result of the lack within the structure and have the permanent trace of the latter. Contingency is shown in this way: as the inherent distance of the structure from itself.
Laclau, Emancipation(s) 1996: 92.
Taken from: Jason Glynos and David Howarth, Logics of Critical Explanation in Social and Political Theory.Routledge, 2007 pp. 128-129.