We conclude that we are justly entitled to regard "the principle of intentionality" as a primary and necessary law of thought, under which we can not avoid conceiving and describing the facts of the universe--the special adaptation of means to ends necessarily implies mind. Whenever and wherever we observe the adaptation of an organism to the fulfillment of a special end, we can not avoid conceiving of that end as foreseen and premeditated, the means as selected and adjusted with a view to that end, and creative energy put forth to secure the end--all which is the work of intelligence and will. [273] And we can not describe these facts of nature, so as to render that account intelligible to other minds, without using such terms as "contrivance," "purpose," "adaptation," "design." A striking illustration of this may be found in Darwin's volume "On the Fertilization of Orchids." We select from his volume with all the more pleasure because he is one of the writers who enjoins "caution in ascribing intentions to nature." In one sentence he says: "The Labellum is developed into a long nectary, in order to attract Lepidoptera; and we shall presently give reasons for suspecting the nectar is purposely so lodged that it can be sucked only slowly, in order to give time for the curious chemical quality of the viscid matter settling hard and dry" (p. 29). Of one particular structure he says: "This contrivance of the guiding ridges may be compared to the little instrument sometimes used for guiding a thread into the eye of a needle." The notion that every organism has a use or purpose seems to have guided him in his discoveries. "The strange position of the Labellum, perched on the summit of the column, ought to have shown me that here was the place for experiment. I ought to have scorned the notion that the Labellum was thus placed for no good purpose. I neglected this plain guide, and for a long time completely failed to understand the flower" (p. 262). [274]
[Footnote 273: ][ (return) ] Carpenter's "Principles of Comparative Physiology," p. 723.
[Footnote 274: ][ (return) ] Edinburgh Review, October, 1862; article, "The Supernatural."
So that the assumption of final causes has not, as Bacon affirms, "led men astray" and "prejudiced further discovery;" on the contrary, it has had a large share in every discovery in anatomy and physiology, zoology and botany. The use of every organ has been discovered by starting from the assumption that it must have some use. The belief in a creative purpose led Harvey to discover the circulation of the blood. He says: "When I took notice that the valves in the veins of so many parts of the body were so placed that they gave a free passage to the blood towards the heart, but opposed the passage of the venal blood the contrary way, I was incited to imagine that so provident a cause as Nature has not placed so many valves without design, and no design seemed more probable than the circulation of the blood." [275] The wonderful discoveries in Zoology which have immortalized the name of Cuvier were made under the guidance of this principle. He proceeds on the supposition not only that animal forms have some plan, some purpose, but that they have an intelligible plan, a discoverable purpose. At the outset of his "Règne Animal" he says: "Zoology has a principle of reasoning which is peculiar to it, and which it employs to advantage on many occasions; that is, the principle of the conditions of existence, commonly called final causes." [276] The application of this principle enabled him to understand and arrange the structures of animals with astonishing clearness and completeness of order; and to restore the forms of extinct animals which are found in the rocks, in a manner which excited universal admiration, and has commanded universal assent. Indeed, as Professor Whewell remarks, at the conclusion of his "History of the Inductive Sciences," "those who have been discoverers in science have generally had minds, the disposition of which was to believe in an intelligent Maker of the universe, and that the scientific speculations which produced an opposite tendency were generally those which, though they might deal familiarly with known physical truths, and conjecture boldly with regard to unknown, do not add to the number of solid generalizations." [277]
[Footnote 275: ][ (return) ] "History of Inductive Science," vol. ii. p. 449.
[Footnote 276: ][ (return) ] "History of Inductive Science," vol. ii. p. 2, Eng. ed.
[Footnote 277: ][ (return) ] Ibid., vol. ii. p. 491. A list of the "great discoverers" is given in his "Astronomy and Physics," bk. iii. ch. v.