Perhaps the deepest, most troubling question about our strange and wonderful existence is this: How did the universe get from matter to mattering? In the meaningless, numb universe of Weinberg, where does mattering come from? Rocks are matter, but nothing matters to rocks. But, without attributing consciousness to a bacterium, glucose matters to a glucose-eating bacterium. What must a system be such that mattering can arise since the brute Big Bang?
Buried in our inquiry are questions that take us beyond physics—if the questions themselves are legitimate. We say, for example, “The function of the heart is to pump blood.” But what then is a “function?” After all, pumping blood is just a “numb” causal consequence of the heart. But the heart also makes heart sounds and jiggles water in the pericardial sac. These too are causal consequences. But they are not functions. In short, functions are subsets of the causal consequences of parts of organisms. But how do we know which ones?
The issue is central to the question of reducing biology to physics. “Functions” in the biological sense, do not exist in physics. Consider a rubber ball. It is round, elastic, can spin on its axis, and it can bounce. But physics cannot say the function of the ball is to bounce. Nor can physics say the function of a river is to flow. Thus, if functions are a legitimate part of biology, then biology cannot be reduced to physics.
Here is an answer: the human heart, as we’ve seen, is part of a human Kantian whole; and of all the heart’s causal consequences, the one that sustains the whole is pumping blood and not making thumping sounds, being red, jiggling water in the pericardial sac, and so forth. So pumping blood is its function—a subset of its causal consequences. Thus both the heart and the organism get to exist and persist in the nonergodic universe above the level of atoms.
More generally, to be a function something must abet the survival of a Kantian whole—like us or a fruit fly or any living thing.
Think again of our self-sustaining, self-creating autocatalytic set of peptides: the function of a peptide is to catalyze the formation of some other peptide and not to jiggle the water in the petri plate. Again, the peptide is part of a Kantian whole, the autocatalytic set, and its function is that subset of its causal consequences that help sustain that whole.
Two large conclusions follow. (1) We can justify the concept “function” in biology because things with functions, for example, hearts, get to exist in the nonergodic universe above the level of atoms by virtue of their role in living organisms—that is, as Kantian wholes that themselves propagate above the level of atoms. So functions are indeed a legitimate scientific concept; (2) the function of a part is typically a subset of its causal consequences, pumping blood and not jiggling water in pericardial sacs.
How different this is from physics. When a stream flows over rocks as it tumbles to the sea, the physicist can describe what happens but can pick out no subset of the happenings as a function. But the function of a peptide in an autocatalytic set, a Kantian whole, is its role in sustaining the catalytic, functional closure of the whole.
To a physicist the pumping, jiggling, shininess, and so forth of the heart are all on equal footing. None of them “matter.”
We will see in this book that what “gets to exist” in the nonergodic universe above the level of atoms and in the evolving biosphere includes ever new, unprestatable “functions” that only come to exist because they abet the survival of the organisms having those functions, for example eyes and sight.
Thus, we are beyond physics for a second reason: physics, in principle, cannot predict these unprestatable new functions, such as hearing and middle ear bones, which come to exist. And so, again, biology cannot be reduced to physics.
The burgeoning diversity that is the biosphere surging upward in complexity for the past 3.7 billion years is surely based on physics, but it flowers to a realm beyond.