Abstract
Abstract Science and technology studies (STS) has perhaps provided the most ambitious set of challenges to the boundary separating history and philosophy of science since the 19th century idealists and positivists. STS is normally associated with `social constructivism', which when applied to history of science highlights the malleability of the modal structure of reality. Specifically, changes to what is (e.g. by the addition or removal of ideas or things) implies changes to what has been, can be and might be. Latour's account of Pasteur's scientific achievement is a case in point. Two polar attitudes towards the world's modal malleability are identified: over- and under- determination, which correspond, respectively, to a belief in the inevitability and the precariousness of science as a form of knowledge. The distinctness of these positions reflects a cordon sanitaire between the history and the philosophy of science. Consequently, historical agents are not given full voice as constructors of reality: They are either quarantined to a foreign realm called `the past' by the historian or selectively assimilated to an imperial present by the philosopher. The second half of the essay explores what it might mean to restore a robust sense of reality construction to the historical agents. My case in point here is that of the 13th century Franciscan friar, Roger Bacon, who has been alternatively seen as a mad medieval or a proto-modernist. To give Bacon full voice would involve taking the future that he envisaged as a normative benchmark for judging our own world.