Over the last month or so, I've been very slowly making my way through volume 2 of Popper's The Open Society and its Enemies. Popper takes to task three philosophers, Plato, Hegel, and Marx, whom he believes promote totalitarianism. In doing so, Popper makes a very strong case against each of their essentialist attitudes, arguing that philosophical nominalism is the only consistent way to gain scientific knowledge.
I had been aware of the essentialist v. nominalist problem for years, but never really understood what it meant. Part of the reason why, I think, was that I associated nominalism with relativism, which it isn't. This may have been because I heard some third hand version of Ideas Have Consequences, which more or less takes such an understanding for granted. In any case, I hadn't put that much thought into it.
Popper first discusses how Aristotle, the connection between Plato and Hegel, argues in favor of essentialism. To Aristotle, all knowledge (in contrast to mere opinion) needs to be based on the correct definition of whatever it is one wishes to learn about. That is, one must understand its essence. The example that Popper uses is, what is a puppy? An Aristotelian would reply, "A puppy is a young dog". The "essence" of a puppy is the fact that it is both young and a dog.
Popper than makes a critical distinction. The essentialist reads the definition from left to right, in his words, "questions are raised by the term that stands, in the definition, on the left side and answered by the defining formula which stands on the right side" [emphasis in original]. The essentialist asks "What is a puppy" and answer it with "a young dog".
Now, to contrast, the nominalist does the opposite, that is, to read the definition from right to left. The question asked isn't "what is a puppy?", but "what shall we call a young dog?"! Popper argues that science cannot and does not ask questions which seek to discover what a puppy is, because "puppy" is nothing more than the name we gave to young dogs! There is never a true essence to "puppy" or "democracy" or "capitalism" or "inflation" because these are all only useful labels we use to refer to "young dogs" or a "society with a representative and elected government" or whatever else. And, if you disagree with, say, my definition of democracy, that is irrelevant. There is no "essence" of democracy, so if my definition differs from yours, all that means is that we each use the same label to describe something different.
I must agree with Popper's argument and with nominalism. I also see nothing but the most naive and superficial connections between nominalism and relativism. More importantly (and disturbingly) are elements of essentialism in the works of many economists I like. For example, economist Murray Rothbard, while defending the concept of natural law, seems simultaneously to be responding to Popper and failing to understand the importance of nominalism to science. Simply substitute "essence" for "nature"
It is indeed puzzling that so many modern philosophers should sniff at the very term "nature" as an injection of mysticism and the supernatural. An apple, let fall, will drop to the ground; this we all observe and acknowledge to be in the nature of the apple (as well as the world in general). Two atoms of hydrogen combined with one of oxygen will yield one molecule of water-behavior that is uniquely in the nature of hydrogen, oxygen, and water. There is nothing arcane or mystical about such observations. Why then cavil at the concept of "nature"? The world, in fact, consists of a myriad number of observable things, or entities. This is surely an observable fact. Since the world does not consist of one homogenous thing or entity alone, it follows that each one of these different things possesses differing attributes, otherwise they would all be the same thing. But if A, B, C, etc., have different attributes, it follows immediately that they have different natures.lt It also follows that when these various things meet and interact, a specifically delimitable and definable result will occur. In short, specific, delimitable causes will have specific, delimitable effects The observable behavior of each of these entities is the law of their natures, and this law includes what happens as a result of the interactions. The complex that we may build up of these laws may be termed the structure of natural law. What is "mystical" about that? [citation]
Maybe, I wouldn't call that "mystical", but Rothbard's description of science certainly isn't correct. Science doesn't set out with questions like "what is an apple?" or "what is it in the nature of apples to do?". Science observes that objects fall back to earth without some other force propelling them from it. Science formalizes the specific manner in which that tendency occurs and calls that behavior "gravity". Science is not in the position to say whether it is in the nature of being an apple to fall towards the earth, nor is it able to tell you "what gravity is" since gravity is nothing but a label attached to a specific observed phenomena.
Rothbard uses this as a basis then to justify "natural law" amongst human beings, as residing within the "nature" (i.e. "essence") of man. While I still have a certain predilection for natural law, Rothbard's starting point (and his subsequent manner of argument) is untenable.
This is, I suppose an indictment of an economist who isn't staying in the realm of economics, per se, but it is an extremely clear-cut example of a mistaken "essentialist" economist. If we take this a step further, are economists justified in asking what the essence of "inflation" is? Or the essence of the "market"? Economics has been defined as the study of the best allocation of scarce resources; does this fallaciously assume an essentialist mode of thinking?