Chapter 6: Irreducible teleology
We’re in the home stretch. In this penultimate section, Feser tries to make the case that teleology, or goal-directedness, permeates the world.
To start with, he tells us that human minds deal with final causes all the time: we conceive plans and execute them, and we build things for specific purposes. So yes, final causes in this sense do exist. But Feser has something much more extensive in mind; not just the existence of final causes, but their ubiquity.
[Biologists] speak, for example, of the function of the heart, of what kidneys are for, of how gazelles jump up and down in order to signal predators, and in general of the purpose, goal, or end of such-and-such an organ or piece of behavior. […] Darwin himself once said that it is “difficult for any one who tries to make out the use of a structure to avoid the word purpose.” [pp. 248–249]
Yes, the appearance of design in biology is compelling, so much so that Richard Dawkins wrote in The Blind Watchmaker that “Biology is the study of complicated things that give the appearance of having been designed for a purpose”. But of course that was Darwin’s great insight, that while we normally think of minds selecting one option or another, with living things, nature itself can, without thought, “choose” which beings reproduce and which ones don’t. That “natural selection” is not an oxymoron.
And yes, it’s difficult to look at nature without seeing design. It’s also difficult to look at clouds without seeing the shapes of people and animals.
Feser gives us a capsule version of evolution:
To say that the kidneys existing in such-and-such an organism have the “function” of purifying its blood amounts to something like this: Those ancestors of this organism who first developed kidneys (as a result of a random genetic mutation) tended to survive in greater numbers than those without kidneys, because their blood got purified; and this caused the gene for kidneys to get passed on to the organism in question and others like it. [p. 250]
One rather absurd implication of this theory is that you can’t really know what the function of an organ is until you know something about its evolutionary history. [p. 251]
Well, no. We can talk of the function of an organ without knowing anything about its evolutionary history, by seeing what the organ does, and what it seems to be good at. For instance, before we start investigating how it is that such-and-such lizard came to be so good at digesting mulberries, it’s important to make sure that it is good at digesting mulberries. Fortunately, we can test this without knowing anything about its evolutionary history.
This is perhaps more obvious in genetics, where we can ask what a gene does, rather than what an organ does. To find out, geneticists typically try to knock the gene out, that is, to raise a generation of fruit flies or mice or zebrafish or what have you that don’t have the gene in question, then see what goes wrong. For instance, when the eyeless gene in fruit flies is damaged or missing, the resulting flies develop without eyes (hence the name).
It gets more complicated than this, of course. Scientists can try to activate the gene in different parts of the body or at different times, and see what happens. Or they can compare different alleles of the gene, or artificially-mutated versions, to see what happens (perhaps it doesn’t control eyes specifically, but all round body parts? Or perhaps it directs each segment to become whatever it’s “supposed” to become?), but this sort of experimentation and observation allow scientists to figure out what a gene (or an organ) does.
Now, this is a bit different from asking what a gene or organ is for. The latter phrasing implies that the gene or organ only does one thing, or has one primary function, and perhaps one or two secondary ones. And while this works in a lot of cases, there are a lot of cases where it doesn’t. For instance, I think it works to say that “the heart is for pumping blood”, because that’s something it does; it also does a good job of pumping blood; it’s the only organ I have to pump my blood, so I rely on my heart to do this; and I can’t do anything else with it. (One might, however, look at it from the point of view of a man-eating tiger, who doesn’t care what I plan to do with my heart. From its point of view, the purpose of my heart is to provide it with nourishment, same as my liver and lungs.)
But what about a bird’s wing? Is it for flight? (Not in ostriches, it isn’t.) Or perhaps it’s for displaying colorful plumage, the better to attract a mate. Or is it for protecting its eggs? Birds do all of these things with wings. And so, I suggest that it’s better to ask “what can you do with it?” rather than “what is it for?” (Besides, think how boring movies like Cast Away or The Martian would be if their protagonists only used things for their intended purpose.)
Now, it may be that when Feser says that a thing is “directed toward” something, he means much the same thing as I do when I ask what that thing is good for. If so, then I think the difference is that I try to allow for the possibility of a thing having multiple uses, while Feser prefers that things have one and only one use. For instance, we saw that he considers sex to have one main purpose — reproduction — and every other use (fun, bonding) is secondary to that.