Principle of Plenitude

I recently encountered a critique of Arthur Lovejoy's well-known book on the "great chain of being."


I've discussed that book in this blog, focusing on what it says about theodicy, that is, efforts to justify the ways of God to man.


But the critic I encountered recently, Jaakko Hintikka, the fellow portrayed here, focuses on the "principle of plenitude."


So let's look at that for a moment, gentle reader. The P of P is one of the "unit ideas" in Lovejoy's account of the great chain. It is one of the atoms that came together to form that molecule.


In Lovejoy's formulation, the P of P is the idea that every kind of creature that is possible is also actual. In one form, this means that in the fullness of time, anything that is not the case now either once was the case or at some time will be the case, as when Descartes wrote that due to the laws of nature "matter takes on, successively, all the forms of which it is capable."


In another form, the principle has a more static significance -- the universe has always included all possibilities within some range. Maintaining this requires a certain level of abstraction in one's formulation, and the level it requires is a matter of some debate. But we can see how the notion of the P of P contributes to that of the Great Chain. There must be matter without life, life without motion, moving life (animals) without intellect, and intellectual animals as well, all because each is possible. Likewise with creatures we cannot observe. There must be intelligences without bodies (angels) because it is possible that there are.


Hintikka contends that Lovejoy's understanding of the P of P is defective "not just in its details but also in some of its main outlines."


He claims, for example, that Lovejoy erroneously believes Plato ascribed to the P of P and that Aristotle did not. On Hintikka's own view, Aristotle not only subscribed to the P of P, he argued for it and used it as a lemma in his philosophy. Whether Plato believed in the P of P, on the other hand, is not at all clear, at any rate he never "embraced" it in an unqualified way as his student did. Given the significance of those two men, this error is more than a detail, even if it is less than a "main outline," of Lovejoy's account.


What is more important, Hintikka contends that Lovejoy is too wedded to a static conception of the P of P. He thinks the more dynamic, evolutionary conception came along quite late in his story. But tis is perhaps because of Lovejoy's premise that the P of P is a true "unit idea." Once we can see that this atom splits, we can see that the dynamic reading was there from very early on.


This will suffice for today's cogitations.