As we use the word science these days, it means something essentially different from the doctrina and scientia of the Middle Ages, different, too, from the Greek ἐπιστήμη. Greek science was never exact precisely because, according to its essence, it neither could be, nor needed to be, exact. Hence, it makes no sense at all to assert that contemporary science is more exact than the science of antiquity. Neither can one say that Galilee’s doctrine of free-falling bodies is true while Aristotle’s teaching that light bodies strive upwards is false. For the Greek understanding of the nature of body and place and of the relation between them rests on a different interpretation of beings. It determines, therefore, a correspondingly different way of seeing and questioning natural occurrences. No one would presume to say that Shakespeare’s poetry is more advanced than that of Aeschylus. It is even more impossible to say that the contemporary understanding of beings is more correct than that of the Greeks. If, then, we wish to grasp the essence of contemporary science we must first free ourselves of the habit of comparing modern with older science – from the perspective of progress – merely in terms of degree.

☛ “The Age of the World Picture” by Martin Heidegger, first delivered as a lecture on June 9, 1938, then published as part of Holzwege, 1950. The quotation above is an excerpt from the English translation: Off The Beaten Track, translated and edited by Julian Young and Kenneth Haynes, Cambridge: Cambridge Univetsity Press, 2002, p. 58 (Scribd, Google Books). In French, the essay is titled “L’époque des ‘conceptions du monde'” and included in Chemins qui ne mènent null part (translated by Wolfgang Brokmeier, éd. Gallimard, Paris, 1962, pp. 99-146; Google books, no preview).

It reminds me of some of the arguments used by Thomas Kuhn in the postscript he added in 1969 to the second edition of The Structure of Scientific Revolution while attempting to defend himself against the accusation of being a relativist.
[UPDATE March 2d, 2011] Professor Hubert Dreyfus noted this similarity as well in a paper he wrote back in 2004 about Foucault and Heidegger:

Heidegger understands our current understanding of being by looking at one of its greatest achievements, scientific research. His account of modern scientific practices is similar to Thomas Kuhn’s in The Structure of Scientific Revolutions. What Heidegger calls research resembles what Kuhn calls normal science. Research operates by setting up a total interpretation of some region of reality and then attempts to show that the anomalies that emerge can be fitted into this total account. Heidegger’s researchers, like Kuhnian normal scientists, keep busy by taking for granted that their general plan is correct; that the anomalies it reveals have no truth to tell, so that in the end they must all be brought under the projected total order. Thus scientific research is made possible by Descartes’ unthought fully focused in Kant, that rationality consists in human beings imposing a total, systematic order on all that is. Heidegger calls this totalizing understanding of being, technological. (“Being and Power: Heidegger and Foucault” by Hubert Dreyfus, 2004)