A writer on Scientific American’s blog, Ferris Jabr, has posted a piece on vitalism, siding with what is a fairly common contemporary position in philosophy: that life cannot be truly distinguished from non-life. It is often assumed that to consider life a separate category, one has to believe in a religious or supernatural component special to living things. In fact, the way Jabr represents Aristotle, it sounds like the Ancient philosopher would agree to such a claim:
Aristotle believed that, unlike the inanimate, all living things have one of three kinds of souls: vegetative souls, animal souls and rational souls, the last of which belonged exclusively to humans.
But this is a misrepresentation of Aristotle’s theory. The exploration of life in Aristotelian philosophy is extensive, and like much of his work, not always fully cohesive, but at least it is clear that “soul” for Aristotle is unhindered by the connotations it has gained through centuries of association with the church. Fabr links to Dan Dennett who does provide a little more clarity, if you read far enough (it’s not that far, but it’s past the first couple mentions of Aristotle’s soul):
“Yes, we have a soul, but it’s made of lots of tiny robots!” … The “tiny robots'” in question are cells (such as neurons) and even tinier robots (such as motor proteins and neurotransmitter molecules) that have evolved to form amazingly ingenious armies of operatives, uniting to form an organization-as Aristotle said-that sustains not just life, like the vegetative soul, and not just locomotion and perception, like the animal soul, but imaginative, rational, conscious thought.
Soul for Aristotle is organization -“the imprint in the wax” in one analogy – and the different kinds of souls he discusses are important aspects of organization in a world he defines as made of substances. So his first distinction is between substances and elements – those things that are organized toward a certain form or purpose (substances), and those that are, basically, “heaps.” The distinction is obvious at higher levels: if you break a rock, or a fire, it becomes (or can become) multiple rocks, multiple patches of fire. But if you break a donkey it will never become multiple donkeys. An element is the same throughout, and a portion of the element is just a lesser amount of the same.
The issue can arise of where plants fit. Sometimes you can split one tree into two, for instance – does that mean they are elements? Aristotle argues that they grow toward a certain form, and that is specific to living things. It has parts and is organized to maintain its form – roots which draw in nutrition, fruits which allow for reproduction, and so on. Of course, we create artificial things which are organized (and it is useful to be aware of the word organ-ized here – this doesn’t mean it has a pattern, but rather that it has specialized parts which work together toward a shared end). Things which human beings make may be organized, but they don’t grow or reproduce themselves. Aristotle’s famous example here is that if you were to bury a bedstead, it might sprout the start of a tree, but it would never grow another bedstead.
We process our artificial creations so much more now that sometimes people are surprised to remember that everything we use began as natural elements, but for the Ancients the difference between natural and artificial was pretty obvious – creatures, trees and rocks in the wild, versus those humans have shaped into usable or desirable items. Has the complexity of technology changed the definition? Well, the fundamental difference is that in nature, the substance is self-organizing, whereas in artifice, we’re the ones putting it together. That seems impossible to get around, but in theory an artificial life could be created and let loose so that our input was no longer necessary – a growing, self-moving, reproducing robot, a car that fixed itself and had baby cars. Without this, a robot that speaks or acts is not lifelike, but only mimicking a few chosen behaviors according to mechanical rules. For Aristotle, life is not simply mechanical. But that doesn’t mean it’s supernatural.
Patricia Churchland is well known for a mechanical view of consciousness, a view which stems from a simplistic dualism that english-language philosophers are a little too likely to embrace: either there must be a magical, inexplicable spirit that inhabits a body, or the body must be a machine just like a car or a computer. What they forget is that artificial machines are our secondary creations, and they are not representative of the full complexity of a living thing. Not surprisingly, this mechanical attitude toward life and consciousness became especially popular in the industrial and technological ages, as humans became more familiar with machines, and spent less time observing nature.
Returning to the Ancient view is useful, and Aristotle’s three levels of soul point out what is specific to life. The starting point is a growing substance, something actively organizing itself toward a unity and able to gather nutrients and dispel waste in the achievement of that formation. The next state is animal life, which adds the ability of perception and self-movement. The third level is temporal awareness and the ability to compare, or rationality. When Churchland suggests that “you are your brain” she is both making an obvious statement and an incorrect one – in fact, you are you, which is to say, the whole thing, although yes, your brain is generally speaking more fundamental than most other parts of you. You could lose both your arms and legs, have many organs replaced by artificial ones, have terrible facial scarring, and still sort of be who you are. But in many very real ways you would lose a lot of yourself. And in truth you could suffer various kinds of brain injury and still sort of be who you are, too. Still, with no brain at all, there would be no starting point, and you could definitely lose a kidney or a finger without it having all that enormous an impact, so comparatively speaking, it’s fair to focus on the brain.
More important is an understanding of what it means to say you are something. When Churchland claims that you are your brain, she almost makes it sound as if, actually, you’re not. Instead, you’re just controlled by it, and it is some mechanical thing that follows its own rules and forces you to behave according to them. But if you are your brain, if it is a full equation, then your brain is you, too. That is, neurons aren’t causing you to act a certain way. Neurons are just the physical manifestation of you. You are causing you to act a certain way.
Of course, psychology is complex and this does not mean you make every choice on a conscious level. Some of “you” is unconscious. Some of “you” is just biological. Often there is conflict, influence, confusion and habit intertwined. But it is still all you in the broadest sense, by being part of one living substance. And this is key to the idea of life – a human being is alive as a substance, and as a rational animal, which is to say that the fundamental activity of nature is recognizable at each level. This has been referred to in a variety of ways, as desire, will, survival of the fittest, emergence, or spark of life, but we do notice that while rocks endure, life thrives. Life isn’t built by external causes but builds itself – grows toward the completion of an intended design, and produces offspring to repeat the plan – and this stage of existence is definitely notable.
Fabr ends by saying that life is “a notion, not a reality”, which will sound a little naive to any philosopher, given that the epistemological stance on other categories is never addressed. Is the difference between a chair and a desk a notion or a reality? What about between a man and a woman, or a fruit and a vegetable? In other words, is there something special about life that makes it less distinct from non-life, or is the point of the article that categories can have edge cases, and are determined by social use and agreement? If it’s the latter, that doesn’t mean our categorizations are useless or don’t point toward important differences. Perhaps as a scientist he is hoping for more quantifiable categories like the elements, and has concluded that life refers to a broader group. But this is not unusual in our referents, nor does it erase the accuracy of the distinction. Just because something can’t be counted does not mean it isn’t perceived and judged. It may be difficult sometimes to decide if a color is orange or yellow, but those occasional tough calls do not lead us to think there’s no way to see colors at all.
In truth, most people are pretty satisfied with the agreed determinations of what we define as life. Crystals do not grow toward a unified form, but are caused by the attachment of multiple parts to one another. Viruses are distinct from parasites in their simplicity and fundamentally secondary nature – one theory of their origin has been that they regressed from parasites, but in current form they lack the substantial nature of biology as they do not feed or maintain an organic identity but rather use the cells they hijack. (Bacteria which are obligate parasites still have their own metabolic processes; they are reliant on environmental factors). Nonetheless, even with disagreements continuing on an edge case like viruses, life is a meaningful category. It isn’t narcissistic to notice that the movement of living things is different from the movement of dead things. It’s just observant, which is one of the qualities of animal life.