Probably we are only now, in the late twentieth century, beginning to realise in a full sense how deeply unsettling this outlook is. For when the claims of reason replaced those of tradition, they appeared to offer a sense of certitude greater than that provided by preexisting dogma. But this idea only appears persuasive so long as we do not see that the reflexivity of modernity actually subverts reason, at any rate where reason is understood as the gaining of certain knowledge. Modernity is constituted in and through reflexively applied knowledge, but the equation of knowledge with certitude has turned out to be misconceived. We are abroad in a world which is thoroughly constituted through reflexively applied knowledge, but where at the same time we can never be sure that any given element of that knowledge will not be revised.

DEFINE: Clarifies 'reflexivity of modernity' — the idea that knowledge applied back onto society is inherently revisable, so certitude is unreachable.

Anthony Giddens, The Consequences of Moderni…, loc. 100