Teleological thinking has been steadfastly resisted by modern biology. And yet, in nearly every area of research biologists are hard pressed to find language that does not impute purposiveness to living forms. The life of the individual organism--if not life itself, seems to make use of a variety of stratagems in achieving its purposes. But in an age when physical models dominate our imagination and when physics itself has become accustomed to uncertainty relations and complementarity, biologists have learned to live with a kind of schizophrenic language, employing terms like 'selfish genes' and 'survival machines' to describe the behavior of organisms as if they were somehow purposive yet all the while intending that they are highly complicated mechanisms.

The present study treats a period in the history of the life sciences when the imputation of purposiveness to biological organization was not regarded as an embarrassment but rather an accepted fact, and when the principal goal was to reap the benefits of mechanistic explanations by finding a means of incorporating them within the guidelines of a teleological framework. Whereas the history of German biology in the early nineteenth century is usually dismissed as an unfortunate era dominated by arid speculation, the present study aims to reverse that judgment by showing that a consistent, workable program of research was elaborated by a well-connected group of German biologists and that it was based squarely on the unification of teleological and mechanistic models of explanation.  In the course of describing the development of this research tradition, I hope to dispell two further misconceptions that prevail in the literature treating early nineteenth century biology. In keeping with the dogma that in the life sciences one is either a vitalist or a mechanist, it is usually assumed that the proponents of teleology are vitalists. My study attempts to show that in the early nineteenth century the central issue was not vitalism as such, but rather the more interesting problem of causality in biology. To the German biologists who fashioned the research tradition discussed here teleological relationships offered themselves as more sensible patterns for investigating the causal relations of organic form and function.  A second assumption challenged by my study is that persons who defended teleological thinking in the life sciences were fundamentally motivated by religious concerns. Several of the figures treated here, such as Immanuel Kant and Johannes Muller, certainly were deeply religious men. Some, such as Karl Ernst von Baer, were not religious in an orthodox sense but held a profound, almost pantheistic reverence for nature. But the issue that motivated them to adopt and tenaciously defend teleological thinking in the life sciences was not religion; it was, I hope to show, a concern for good science.