 The basic Kantian insight was further ramified by Lotze: mechanism and teleology are coexisting, compatible modes of explanation, each with their own proper sphere, and not contradictory opposites: “[b]oth … are limited, and both imply one another. Mechanism is therefore no power controlling reality, but rather the way in which a purposeful reality realizes itself” (Robins, 1900, p. 11). A lazy reliance on hypothetical posits, Lotze suspected, merely betrays our unwillingness to engage in the difficult work of real scientific discovery. Furthermore by “mechanism” Lotze meant not a blind naturalistic or reductionist technique; rather, he used this word to signify a hypothetical-deductive method of explanation of phenomena (cf. Woodward &amp; Pester, 1994, p. 165). This has important ramifications for the emerging biological sciences: if the essence of science lies in the employ of the hypothetical-deductive method of explanation—and not mathematization, as Kant had insisted—then biology and medicine, for instance, both might admit of a rigorous treatment worthy of the name ‘science’. Teleology does not replace explanation: it supplements it (cf. Lenoir, 1982, pp. 168ff).