THE DOCTRINE OF FINAL CAUSES. 487 



nave remained unassailable so long as the question was a professional 

 one ; and the discussion is open to those who possess no peculiar 

 knowledge of anatomy. We shall, therefore, venture to say a few 

 words upon it. 



Sect. 2. Estimate of the Doctrine of Unity of Plan. 



IT has been so often repeated, and so generally allowed in modern times, 

 that Final Causes ought not to be made our guides in natural philoso- 

 phy, that a prejudice has been established against the introduction of 

 any views to which this designation can be applied, into physical spe- 

 culations. Yet, in fact, the assumption of an end or purpose in the 

 structure of organized beings, appears to be an intellectual habit which 

 no efforts can cast off. It has prevailed from the earliest to the latest 

 ages of zoological research ; appears to be fastened upon us alike by 

 our ignorance and our knowledge ; and has been formally accepted by 

 so many great anatomists, that we cannot feel any scruple in believing 

 the rejection of it to be the superstition of a false philosophy, and a 

 result of the exaggeration of other principles which are supposed capa- 

 ble of superseding its use. And the doctrine of unity of plan of all 

 animals, and the other principles associated with this doctrine, so far 

 as they exclude the conviction of an intelligible scheme and a disco- 

 verable end, in the organization of animals, appear to be utterly erro- 

 neous. I will offer a few reasons for an opinion which may appear 

 presumptuous in a writer who has only a general knowledge of thf> 

 subject. 



1. In the first place, it appears to me that the argumentation on the 

 case in question, the Sepia, does by no means turn out to the advan- 

 tage of the new hypothesis. The arguments in support of. the hypo- 

 thetical view of the structure of this mollusc were, that by this view 

 the relative position of the parts was explained, and confirmations 

 which had appeared altogether anomalous, were reduced to rule ; for 

 example, the beak, which had been supposed to be in a position the 

 reverse of all other beaks, was shown, by the assumed posture, to have 

 its upper mandible longer than the lower, and thus to be regularly 

 placed. " But," says Cuvier, 13 " supposing the posture, in order that, 

 the side on which the funnel of the sepia is folded should be the back 

 of the animal, considered as similar to a vertebrate, the brain with re- 



G. S. H. Phil. Zool. p. 70. 



