In this chapter, I derive the same understanding of causality as in the previous chapters but from a different starting point, that of biology.

While causality can have many complicated definitions, in biology it is often understood simply as being the opposite of teleology. In other words, causation is when events from the past influence the present, whereas teleology is when the future is what influences the present in the form of fate, predestination, or actions working toward a goal. It turns out that it is easy to see teleology in biology—it is easy to see things seeming to work towards a goal—and so it requires some explanation or justification to believe in causality, instead. That was a major controversy in the 19^th Century.

Teleology, more exactly, was often associated with the word “design.” The reason that things seemed to be working towards a goal was that they were designed to work that way. They were designed to behave as if having a purpose which we can recognize, even as we also might realize that the situation is very complicated, so much so as to be even sometimes beyond our understanding, (That is, we might not know how it works, but we can still recognize how it has a purpose, such as how the purpose of the heart is to pump the blood). Historically, such a belief was often held by scientists (Mayr 1982) since seeing the purpose in things such as the heart was consistent with direct observation. Among 19^th Century scientists, teleology (finding the purpose in things) was also held to be the “only really scientific evidence” for the existence of God (Mayr 1982, 528) since scientifically describing the design in things was scientific evidence of “God’s plan” in the world.

And finding purpose in things does happen over and over again in biology. (The purpose of a flagellum is locomotion; the purpose of DNA is to store information). Indeed, the mantra in biology, upon discovering a new feature, is to ask, “What is its structure, and what does it do?” (Campbell 1996). But answering the second part of that mantra seems (at first, at least) to imply teleology, purpose, and design.

That is even more explicit when biologists formally use the word “function,” as in “What is its structure, and what is its function?” That is because the word “function” strongly implies “purpose,” as in “What was it designed for?”

That was so much the case that well into the 20^th Century people who did not believe in design cautioned against using the word “function” at all, holding that the word was misleading and should be taboo. The reason was that, according to these reductionists, all that really exists in biology are atoms and other particles obeying the laws of science, and so for our minds to find functions in the world was really just our minds playing tricks on us.

However, biologists would have nothing to do with that argument, and the reason was precisely because talking of functions was indispensable to their work. How could they describe, say, the lungs without describing their function of breathing? How could they describe any part of the body without answering, “What does it do?”

As the biologists put it, “Form fits function” (Campbell 1996, 9). The structure of a living thing is correlated with its function. Biologists could not describe just a structure alone.

So it became indispensable to find an alternative explanation for things in biology having functions, besides teleology and design.

And historically the opposing doctrine was causality and “natural forces.” According to this argument, the reason that organs act as they do is that they are following laws which produce causality and natural forces, both of which push things around, including pushing around organs in a manner that appears to our minds as the organs having purposes. And that explanation, of course, leaves out the part about “God’s plan.”

So the issue became: Which was right, causality or teleology? Indeed, if we took our cue from Occam’s razor, the doctrine that the simplest explanation is the best explanation, then it would seem that that favored teleology. By direct observation, body organs have functions. But to attribute that to causation and natural forces required positing atoms (this was before atoms were discovered), and it required a belief in unseen activities (because atoms were too small to be seen doing things).

Historically, the view which came to predominate, however, was the one that worked by natural forces, and that can be directly attributed to the success of Darwinism. Darwinism shows how natural forces can evolve complicated organs without requiring a “plan” Although today it is often heard that the complaint over Darwinism was that it contradicts Biblical accounts of the creation of the world, to the 19^th Century scientists who took teleology as scientific evidence for the existence of God, what was devastating was that Darwinism contradicted, not the Bible, but teleology (Mayr 1982, 528).

But then how are functions explained today?

It turns out that there are also atheists who believe in teleology because it seems to them that things really do appear to act with purposes. (How can we deny, they ask, that the purpose of the heart is to pump the blood?). A contemporary example of such an atheistic teleology is the philosopher Thomas Nagle (see Nagle 2012), and a historical example is Aristotle (whose “final cause” was teleological).

One argument against such secular teleology is that it requires minds to see the purposes and functions and so the functions are not really in the physical Universe; they are just concepts of the mind. But the counter to that argument is to point to how the function of the eye is seeing and to ask, “Is ‘seeing’ really just a concept?” Or look at the lungs and ask, “Is breathing just a concept?”

Darwinism has tipped the balance in biology in favor of natural forces over teleology. But that has not eliminated the philosophical issues. We still need to explain how seeing is more than just a concept. Or conversely, we need to tell why is it okay to speak of functions at all.