pertise ought to be managed, and, while in general I like the idea of opening up decision-making processes to a range of interested parties, I am not comfortable with the notion of ethical expertise. For all that, I do not expect that my personal views on such matters ought to be of the slightest interest to anyone.

It is, rather, as an historian of early modern science and as a sociologist of scientific knowledge that I feel I might have something to contribute to contemporary debates over science and ethics. I want to draw attention to how the modern state of affairs just outlined came to be. Historical perspectives occasionally have the capacity to encourage a more disengaged look at present predicaments, while the fact that the divorce between expertise and virtue is, as I shall indicate, a strikingly recent one can prompt the thought that there may be some point in seeking to "unwind" a bit of history. There is nothing inherently "natural" about the late-twentieth century distinctions between virtue and scientific knowledgeability. The historical record offers a vision of alternative arrangements. Moreover, the same historical perspective can suggest that the modern disengagement between virtue and expertise may be more in the appearance than the reality. To the extent that we accept such a disengagement as real, right, and proper, I suggest that we are storing up problems not just for scientists' moral authority but for their credibility.

Indeed, I want to approach the problem of scientists' moral authority by way of an historical inquiry into their credibility, the grounds on which scientists' pronouncements about the natural world are taken as true, objective, or reliable. Just because personal morality and knowledgeability are so widely considered as distinct in the modern condition, I start by outlining a scheme of things in which they were not reckoned to be so in the past. I shall describe a culture in which the credibility of scientific claims and the moral standing of those who make the claims are intertwined. Specifically, I mean to describe a relationship between credibility and virtue by drawing attention to the importance of trust relations in the making of scientific knowledge. I suggest that while those trust relations continue to be vitally important in modern science it has become harder and harder to appreciate them. One consequence of the invisibility of trust is the very attitude towards the disengagement between virtue and expertise which gives our modern dilemma its basic shape.

Why do we believe what scientists tell us about the natural world? Why do we trust them to tell the truth? The fact of that trust, as well as its enormous extent and consequences, should be in no doubt. Most of our formal knowledge of the natural world is derived from no other source