Aristotle’s ‘four causes’
Aristotle insists, against what he sees as the narrowness of previous philosophers, that there are four ‘causes’ which the enquirer into nature should make use of. What he has in mind is the different ways in which we explain natural processes and things, and he is insisting that there is not just one type of explanation, but many, which do not exclude one another. Aristotle’s theory, though, is about the way the world is and not just the way we explain it; the four so-called ‘causes’ are different kinds of item which figure in what he thinks are the four fundamental types of explanation of nature.
One is the material cause or matter, the physical make-up of the thing, which puts considerable restrictions on what it can be and do. The second is the form. Aristotle gives examples of artefacts where the form is the shape, but in the case of a living thing the form is more complex: it is, very roughly, the way of being alive which defines that kind of thing. The form of an oak tree is whatever it is which explains why the tree lives and grows as an oak- from acorns, for example, and only in certain climates. Thirdly is the moving cause, the item initiating a change. Fourthly is the final cause or end, what the thing or process is for, something that has to be cited in showing how it functions.
Modern theories of causality have very different aims and assumptions, and would count only Aristotle’s moving cause as a cause (and only with qualifications).
Aristotle, as often, does not think that this story is completely wrong; we do need the right kind of physical embodiment. But on its own it is inadequate to explain why we always (or nearly always) find that animals are well adapted to the lives they lead, and that their parts are formed in a way which performs the appropriate function. Teeth, for example: we find the sharp incisors at the front of the mouth, for tearing, and the blunt molars at the back, for chewing. We always find this, because it is a good arrangement for the animal. Unless something has gone wrong, we don’t find animals struggling with bad arrangements (molars at the front, for example). Random happenings, Aristotle thinks, are quite inadequate as an explanation of how we get to the universal well-adaptedness to environments and lifestyles that we find among animals. Thus, he concludes, our explanations have to include what the thing is for. Aristotle does not think that this is always appropriate: there is nothing, for example, that horses or camels are for. The level of explanation that concerns him is that of the parts of animals. Hearts, for example, are for pumping out the blood to the rest of the body; blood, in turn, is for carrying nutriment to the body.
Aristotle’s is an especially interesting position, because we can now appreciate both that he is wrong, and that at the time he had the better of the argument. In the absence of any plausible mechanism for getting to (almost) universal well-adaptedness from random happenings, as well as the absence of any idea of geological time, Aristotle is right in thinking that present well-adaptedness cannot be accounted for merely by random happenings. After Darwin’s work, we can see why we are not compelled to an Aristotelian view by the kind of consideration that Aristotle stresses.
Aristotle’s teleological approach is the source of his most sympathetic insights. In plants, he comments, the roots have the function that the head has in animals; but we should not think of plants as growing upside down, since what is up and what down depends on the kind of thing we are talking about. Crabs are the only animals which move sideways; but in a sense they are moving forwards, since their eyes are so positioned that they can see where they are going. In these and many other cases Aristotle frees himself from human ways of thinking of things like nutrition and movement to observe how well the species functions from its own point of view.
Aristotle’s thoughts about teleology have nothing to do with the idea that purposes in nature are the product of design – indeed, for him this would be inappropriate projection of human concerns onto nature, shaping nature in our image in an absurdly pretentious way. But Aristotle’s was not the only version of teleology available in the ancient world.
In his dialogue Timaeus, Plato presents an account of the universe as created by God, who is a craftsman and who produces our universe in the way that a craft worker creates an artefact, by imposing form and order on materials which are more or less satisfactory for the task. Plato holds that the materials available to God for making the world are inherently unsatisfactory and perhaps even refractory, since our world is created to a good plan, but contains failure and evil.
It is uncertain, and was much discussed in the ancient world, whether Plato had in mind an actual creation or was merely giving an analysis of the ways things are, but certainly the overall picture is one in which our world is not just created, but created to carry out an intellectual design on the part of a creator. Moreover, not merely the general principles of cosmology, but some quite specific details, particularly concerning humans, are explained in terms of overall design. The fact that humans walk upright, and have roughly spherical heads, is explained by reference to our being rational in a way that other animals are not; the explanations, as we might expect, are extremely fanciful.
The Timaeus, however, presents itself not as serious cosmology but merely as a ‘likely story’, an example of the kind of account that Plato thinks is the right one to give; it is poetic and grandiose in style. And the account it gives is also very openly ‘top-down’, working through the consequences of a few very general principles; Plato shows no interest in satisfying the observations we make in our experience, or in making any himself.
The Stoics picked up on Plato’s account of the world as the creation of a designer God, and developed it, though in a somewhat different direction. Their conception of God is different; for them God is to be thought of not as a creator of the world, but in a more impersonal way. God is simply the rational organization of the world, and so should not be thought of on the model of a person (though the Stoics allow that popular religion, which accepts several gods, is a dim grasp of the idea that the world is structured by reason and intelligence).
The Stoics therefore take a different tack from Plato’s appeal to the idea that God is like a craftsman. They appeal to evidence in the world that suggests that it is the product of design and rational ordering. They reject the idea that the world is the product of random events and forces, on the grounds that it is implausible – like, they say, the idea that random distribution of letters of the alphabet could produce a poem. (Note that this argument is different from Aristotle’s; he denies that random events could produce regular well-adaptedness, whereas the Stoics deny that random events could produce good design.)
Some of their arguments for design in the world appeal to the sheer complexity of natural objects. Suppose, one argument goes, that a complicated mechanism like a clock were shown to people unfamiliar with it; they would still recognize it as the product of a rational being. Hence, natural objects, which display a greater complexity and suitability for their function than artefacts, must be the product of reason – clearly a reason greater than ours, one embodied in the universe as a whole. (This is strikingly similar to the ‘argument from design’ common among Christian thinkers before Darwin.)