Who Sez There's No Telos in Nature?

 

(Photo from Conversion Diary)

when even plants strive toward something beyond themselves? 

Without this "towardness" there would be no laws of nature, since there would be no reason why A→B "always or for the most part."  Efficient causes thus depend on finality for their coherence. This is why final causes have been called "the cause of causes." 

In particular, evolution (transformism) would make no sense without this intentionality of living things, since the efficient cause (natural selection) would at best simply weed out the unfit.  It is precisely the striving of living things to go on living that leads them to exploit new mutations and new environments.  To seek out new life and new civilizations; to go where no....  Wait a minute.    OK.  Natural selection, as an efficient cause would not necessarily select for better fitness unless there were an intentionality in living things, a towardness in nature for better fitness. 

Further, the formal causes of the new species exist potentially in the old.  For example, the form of new species, exemplified in part by their genome, exist in potency in the genome of the ancestral species, as the word c-a-t exists potentially in the word c-u-t.  That is, by power of mutation, the one may evolve ("roll out") from the other. 

Thomas Aquinas touched on the issue tangentially during a discussion of other matters. 

Objection 3. Further, nothing is said to be complete to which many things are added, unless they are merely superfluous, for a thing is called perfect to which nothing is wanting that it ought to possess. But many things were made after the seventh day, as the production of many individual beings, and even of certain new species that are frequently appearing, especially in the case of animals generated from putrefaction.

Reply to Objection 3. Nothing entirely new was afterwards made by God, but all things subsequently made had in a sense been made before in the work of the six days. .... Species, also, that are new, if any such appear, existed beforehand in various active powers; so that animals, and perhaps even new species of animals, are produced by putrefaction by the power which the stars and elements received at the beginning. ....

-- Thomas Aquinas, Summ.Theol. I, 73, 1, ad. 3 et resp. 3

Now, Thomas was relying on science that we now know was wrong.  Pasteur and others showed much later that living things do not in  fact arise from non-living things.  But the example is purely illustrative.  Thomas clearly states that new species (implicit or potential in the old) are brought forth by purely natural powers; and this would be the case whether it really was the stars and the elements causing putrefaction or cosmic rays from the stars causing a mutation in an element of a genome.  He did not suggest that new species arose because of a violation of natural law.