Modes of Life
The living vs the inanimate
Having got through talking about being and bodies, it is now time to discuss the special type of body called the "living body." In this, we are following the Aristotelian arrangement of things, where his works on living things come after his works on inanimate nature--and this seems to be the way he considered them and is not just the way an editor compiled his notes.
But there is a difficulty with this that followers of Aristotle like St. Thomas did not fully resolve: If you consider living things a special case of bodies, then you run the risk of making a definition of "life" that applies only to bodies, even though investigation indicates that living bodies are alive to the extent to which they are less dependent on their bodiliness--which would allow one to extrapolate and say that purely spiritual beings, and certainly God, should be allowed to be called "alive" also, and perhaps in a truer sense, than living bodies.
But if, for instance, you define "life" as "self-initiated process" ("self-movement") in the way Aristotle did, then pure spirits, as we saw in the last chapter of the preceding part 2.3.7, cannot be living, because they are necessarily in absolute equilibrium, and so cannot undergo process, whether self-initiated or not. St. Thomas, who held that God and angels were alive, got round this by taking "process" in that extended sense which includes acts in equilibrium within it, and pointing out that spirits will their own acts and their own being, and so are "self-initiated acts" in an analogous sense.
But since God's life is supposed to be the paradigm of life, and since God is absolutely immutable (and St. Thomas held this), then it seems that the definition of life involving change is just wrong, even though you may be able to justify it.
In any case, I think that Aristotle came up with the wrong definition because he was focusing on bodily life, and defined it it terms of a property of bodily life as bodily, rather than hitting on what it was about life that accounted for the self-initiated processes in bodies. And if a mind of the stature of Aristotle's fell into this trap, we will have to keep our eyes open not to do so ourselves. Of course, we are forewarned, and he wasn't.
The approach here is going to be to notice the properties that living bodies have that inanimate ones don't; and since properties reveal the nature, and the nature is the structure or essence insofar as it can perform the acts in question, then the properties that living bodies have should reveal something about their structure as living; and so based on these properties, we can probably come up with a definition of life which will apply to all living beings.
We will start with the properties that all living bodies seem to possess: those of nutrition, growth, reproduction, and repair of injuries--the so-called "vegetative properties"--and go on from there to investigate consciousness, first in general, and then in its form that is shared by animals and humans, and finally in the human acts of understanding and choosing, which as far as we know are unique to humans among animals. We will see that these imply higher forms of life and higher types of existence, and these forms of life will confirm the hypothesis we will form at the vegetative level about what life is.
We will also continue the practice, begun in the first part, of commenting on God in the light of what we discover about the finite. Here we are going to be able to do a bit more in making affirmative statements about God, because life and consciousness belong to things insofar as they are not limited quantitatively, and become greater or "truer" as they get less limited; and so these are probably properties of existence insofar as it is not limited, and so apply in the fullest sense to God. When we were talking about bodies, except for things like "existence" itself or "activity," then we were talking about types of limitation, and so all that we could assert is that God did not have the characteristic in question, such as form or quantity or position, and so on.Next