If we read Kant's Criticism of the Teleological Faculty of Judgment, his most important biological work, we perceive that in contemplating organic nature he always maintains what is essentially the teleological or dualistic point of view; whilst for inorganic nature he, unconditionally and without reserve, assumes the mechanical or monistic method of explanation. He affirms that in the domain of inorganic nature all the phenomena can be explained by mechanical causes, by the moving forces of matter itself, but not so in the domain of organic nature. In the whole of Anorganology (in Geology and Mineralogy, in Meteorology and Astronomy, in the physics and chemistry of inorganic natural bodies), all phenomena are said to be explicable merely by _mechanism_ (causa efficiens), without the intervention of a final purpose. In the whole domain of Biology, on the other hand--in Botany, Zoology, and Anthropology--mechanism is not considered sufficient to explain to us all their phenomena; but we are supposed to be able to comprehend them only by an assumption of a _final cause_ acting for a definite purpose (causa finalis). In several passages Kant emphatically remarks that, from a strictly scientific point of view, _all_ phenomena, without exception, require a mechanical interpretation, and that _mechanism alone can offer a true explanation_. But at the same time he thinks, that in regard to living natural bodies, animals and plants, our human power of comprehension is limited, and not sufficient for arriving at the real cause of organic processes, especially at the origin of organic forms. The _right_ of human reason to explain all phenomena mechanically is unlimited, he says, but its _power_ is limited by the fact that organic nature can be conceived only from a teleological point of view.
Some passages are, however, very remarkable, in which Kant in a surprising manner deviates from this mode of viewing things, and expresses, more or less distinctly, the fundamental idea of the Theory of Descent. He even asserts the necessity of a genealogical conception of the series of organisms, if we at all wish to understand it scientifically. The most important and remarkable of these passages occurs in his "Methodical System of the Teleological Faculty of Judgment" (§ 79), which appeared in 1790 in the "Criticism of the Faculty of Judgment." Considering the extraordinary interest which this passage possesses, both for forming a correct estimate of Kant's philosophy, as well as for the Theory of Descent, I shall here insert it _verbatim_.
