Central to Aquinas’s whole metaphysical system, and even central to his whole project of metaphysics, is the belief that essences are real. This is known as essentialism. Modern science and philosophy, however, have come so far from the common sense position that things have essences that to even ask the question is seen as a waste of time. This post is meant as a brief introductory look at an overview of arguments that could be presented in favor of an essentialist position.
By far the greatest reason to affirm essentialism is that it is just our starting point for understanding, describing, and interacting with reality. Whether we realize it our not, we are all at least implicit essentialists: we all look at and talk about reality as if there really are things with intrinsic unity which are distinct from other things and other kinds of things. This tree, that rock, those birds, etc. From childhood this is just our natural disposition in relation to the world. We understand that the things we observe and experience have a whatness about them that makes them what they are and separates them from other things; and this natural understanding is constantly supported by experience. So much so, in fact, that Aristotle thought it was worthless to even attempt to offer arguments in favor of essentialism, because it is just something so obvious that arguments aren’t even needed. Indeed, he compared trying to prove that things have essences/natures to trying to prove that colors exist:
“That nature exists, it would be absurd to try to prove; for it is obvious that there are many things of this kind, and to prove what is obvious by what is not is the mark of a man who is unable to distinguish what is self-evident from what is not. (This state of mind is clearly possible. A man blind from birth might reason about colours. Presumably therefore such persons must be talking about words without any thought to correspond)” (Physics 2.1, 193a1-8) .
As philosopher Edward Feser notes, that Aristotle thought it absurd to attempt to prove the reality of natures/essences was not a reflection of him thinking “that it is doubtful that things have natures or essences, but rather that it is obvious that they do — indeed, that the belief that things have essences is more obviously correct than any argument that can be given for or against it” . Nevertheless, since essentialism has become so overwhelmingly contested, it is necessary to attempt exactly what Aristotle vehemently suggested we not: offer arguments in favor of the reality of essences.
First, of course, we should have at least a general idea of what we mean by essence. In a very simplistic sense, an essence is just what something is — it’s “nature” or “quiddity”, that whereby or through which it is a certain kind of thing and not another. As Feser explains, an essence “is what we grasp intellectually when we identify a thing’s genus and specific difference” . The classical example is Aristotle’s definition of the human essence: to be human is to be a “rational animal”. “Animal” designates the (logical) genus in the definition, the larger group/class which provides a framework for understanding what type of thing a human; and “rational” is the species or specific difference, that which separates humans from everything else in the class of animals. To understand this definition of humanity is to understand what humans are, and hence to know the essence of a human, that which makes some existing thing a human as opposed to the infinite number of other possible things it could be. Essentialism is the position that things in the world really do have such essences, objectively and mind-independently. In other words, a tree would really be a tree, in itself, whether or not humans existed to ever understand the concept of “tree”.
So, besides the fact that it is constantly and overwhelmingly experientially confirmed, and despite the fact that we could barely make sense of the world without it, what reasons are there for affirming essentialism?
The first is that it provides a solution to the problem of the one and the many. The world we experience consists of a vast plethora of different beings: trees, dogs, cats, rocks, planets, mountains, etc. We recognize each of these as something distinct from the others. A tree is not a dog is not a cat is not a rock, etc. But within this vast plethora of distinct objects, we also recognize that different beings share similarities, there there is some sort of unifying principle in kinds of things. In other words, we know that there are thousands of different particular or individual trees, but there is something about all of these distinct, individual things that enables us to label them under the same class. This particular tree and that particular tree and all the other particular trees are all really trees; there is something about them which unites them in a common understanding of definition. The same is true all across the spectrum of being: animals, plants, and, most significantly, humans. Furthermore, this principle is not only a unifying one but also a distinguishing one. In other words, whatever it is about all the different particular trees that allows us to understand them as in some sense sharing a unity/commonality is precisely what allows us to distinguish all the particular trees from all the particular kangaroos or otters or flowers. Whatever it is that makes this object a tree is precisely what makes it not every sort of non-tree. If there were not such a principle, that is both unifying and distinguishing, we would be left with no satisfying solution to the problem of the one and the many .
“These groups of things manifest common causal powers and other properties in just the way we would expect if there were a common real essence or nature they all instantiated, but which would be mysterious . . . if their being grouped together was merely a matter of human convention” .
This quote points out how it is that we recognize distinct types of beings: common causal powers, properties, capacities, etc. This too is further evidence of things having real essences. Essences explain the unifying principle that acts to unify all particular instances of a kind (e.g. all individual trees), but essences also explain the intrinsic unity of the individual things themselves. We understand that this tree is a tree, a single, unified whole despite the fact that it might be made up of many different intricate parts. The strongest (and indeed undeniable) evidence for this point is our own introspective self-experience. Now matter how many times one tells you that you are “just a collection of atoms and molecules”, you will always experience reality as a unified whole, as a being and an individual. Feser comments on this second notion of essence as unifying principle:
“Each individual thing exhibits a unity of its own . . . [Each will] behave over time in a uniform and predictable manner, exhibiting characteristic properties and patterns of operation, persisting despite changes in superficial features, and having parts that function in an integrated way. This too is just what we would expect if each of these things had a real essence or nature, and would be mysterious if what we thought of as their essences were merely a matter of human convention” .
Philosopher Brian Davies also refers similarly to this unifying principle (though his account which I am quoting here is more modest, since he is largely dealing with the problem of evil and isn’t trying to offer an in depth defense of essentialism or the existence of God):
“We live in a universe in which things can intelligibly be singled out as subjects to be studied, categorized, analysed and described. We live in a universe made up of distinguishable, concrete things (some made up of distinguishable parts, some not), thing we can refer to and to which we can apply predicates” .
A more in depth defense of essentialism argues that positing that things have real essences/natures is not only supported by modern science, but is actually perhaps even necessary for the whole modern scientific enterprise. Aristotle recognized that physics or natural science in general is primarily an inquiry into the natures of things. Early modern science tried to escape from this, framing its method more in terms of quantitative descriptions of regularities; but recently philosophers of science have been becoming increasingly aware of the need for something like natures or essences to make sense of the scientific endeavor .
This is seen immediately in the relation between scientific descriptions and universals:
“Scientific laws and classifications, being general or universal in their application, necessarily make reference to universals; and science is in the business of discovering objective, mind-independent facts. Hence to accept the results of science is to accept that there are mind-independent universals” .
Science deals with universal descriptions. And these universal descriptions must be rooted in real, universal essences. It is difficult to see how we could make sense of references to “atoms”, “electrons”, “protons”, “neutrons”, or classifications of living organisms, chemical elements, etc., unless these descriptions reflected real, intrinsic essences in those things. Science would lose all its efficacy if it could not point to different particular atoms and hold that their is something really common and unifying about all of them together; otherwise it could not offer any general descriptions at all, at least meaningfully.
As Feser points out, contemporary philosophers of science have “argued that physical science is in the business of discovering essences as well as causal powers, insofar as the powers science aims to uncover are powers things have essentially” . Modern physics works to uncover the operative powers of things, and these powers must be rooted in the essences of things. Furthermore, some have even contended that powers of this kind, rooted in essences, “are necessary in order to ground laws of nature” . As was said above, modern scientific methods offer general descriptions of what is often referred to as “laws of nature”. The “fundamental forces” (electromagnetic force, strong nuclear force, etc.) which seem to ground most of the “laws” or regularities in nature are the result of the interaction of subatomic particles: in other words, the “laws of nature” are ultimately determined by the regular tendencies or powers of things, and these regular/natural tendencies, powers, and properties must be grounded in the intrinsic nature or essence of those things .
As one contemporary philosopher of science has expressed, particularly in relation to chemistry:
“Every distinct type of chemical substance would appear to be an example of a natural kind, since the known kinds of chemical substances all exist independently of human knowledge and understanding, and the distinctions between them are all real and absolute . . .These differences were not invented by us, or chosen pragmatically to impose order on an otherwise amorphous mass of data. There is no continuous spectrum of chemical variety that we had somehow to categorize. The chemical world is just not like that. On the contrary, it gives every appearance of being a world made up of substances of chemically discrete kinds, each with its own distinctive chemical properties. To suppose otherwise is to make nonsense of the whole history of chemistry since Antoine Lavoisier” .
Essences are required to make sense of distinct kinds of chemical elements, as well as other distinct kinds of things already mentioned — kinds of things with unique causal powers, properties, capacities, etc., that make it that kind of thing as opposed to another. To deny essentialism is to deny that there really are such distinct kinds of things in the sense that the kinds have intrinsic, mind-independent factors which define them and make them what they are.
It will not do, moreover, to say something such as “A molecule of water has no essence, because what makes it what it is and separates it from other things is just the unique chemical bond it has consisting of the interaction of hydrogen and oxygen atoms.” This is not an adequate refutation of essentialism, and indeed it might even implicitly affirm essentialism. To say that a water molecule is a specific kind of thing with an intrinsic nature is not to deny that that nature might materially just consist of a chemical bond between interacting hydrogen and oxygen atoms. On the contrary, affirming that water molecules generally are things which consist of chemical bonds between interacting hydrogen and oxygen atoms is to affirm also that water molecules are real types of things that are different from other types of things, including oxygen and hydrogen atoms. And if a water molecule is a real type of thing different than other types of things, whose difference derives from some objective, intrinsic aspects about itself, then it has an essence.
It seems to me that even on a materialistic reductivism some type of essentialism is incredibly difficult to avoid. Suppose, for instance, that the view of the ancient atomists were correct, that the whole universe is just comprised of various formulations of basic atoms, and that these atoms are the absolute most fundamental substances/building blocks. They are entirely simple and non-composite, not made up of any parts or anything more fundamental than themselves. Everything else in the universe, however, including all the objects of our experience, are just made up of different arrangements of these atoms. An atomist who holds to this view might deny that all these objects have essences — dogs, lizards, trees, etc. — but it seems impossible for him to deny that the atoms themselves have essences. Indeed, he is asserting that all the individual atoms share some commonality which allows us to understand them as a single type of existing thing. If he were to deny this, he would have to hold that not only is each individual atom different in particularity from all the others (i.e. that this particular instance of an atom is different from that particular instance of an atom), but also more radically that each individual atom is a completely and absolutely different type of thing than every other atom, which seems preposterous. But even then, he would be affirming that each and every atom is in itself its own kind of thing, and hence that each and every atom has its own essence.
There are other arguments for an essentialist position as well. If substantial forms are real, then this in itself is a further argument for essentialism, for “What could it mean to say that a thing has an intrinsic principle of operation, that its operations are intrinsically ordered to certain ends, etc., but that there is no mind-independent fact of the matter about what kind of thing it is?”  (I’ll be defending substantial forms in a future post).
Finally, and perhaps even most significantly, I think an argument can be made for essentialism from ethics and human dignity. We have commonly held notions/values of “human rights”, “human dignity”, and “human value” which become absolutely meaningless if there is no such thing as a real, objective human nature. In other words, if “humanity” is a fictitious, mind-dependent concept we’ve invented, then it seems impossible to consistently hold that it could ever be objectively wrong to murder or harm other human beings. If there is something intrinsically valuable about human persons which accounts for their dignity, worth, and rights, then there must be such a thing as a common and objective human essence.
Several points should be made in conclusion. First, essentialism is a metaphysical and ontological claim, not an epistemological one; i.e. essentialism is the claim that essences exist, that things really have essences, whether or not we can actually know those essences. Classical essentialists were often extremely modest and cautious in identifying what things actually have essences and what those essences were. Essentialists today disagree on this issue: some think that just basic things have essences, up to perhaps the chemical level. More commonly, the belief is held that living organisms also have essences (especially humans, in light of the argument just given). But epistemological skepticism about essences should not translate to an ontological denial of essences.
Secondly, this post is meant as a very brief and general overview of some different types of arguments that might be offered in defense of essentialism; it should not be taken as a definitive or exhaustive case. It is a complicated subject debate over which has been being engaged for nearly three thousand years. Nevertheless, I think what has been presented here should suffice to show that there are indeed good reasons to hold to essentialism.
. McKeon, Richard, editor. The Basic Works of Aristotle. New York: Random House, Inc, 1941.
. Feser, Edward. Scholastic Metaphysics: A Contemporary Introduction. Piscataway: Editiones Scholasticae/Transaction Books, 2014. Print, 212.
. Ibid. 211.
. For more on this, see Clarke, W. Norris. The One and the Many: A Contemporary Thomistic Metaphysics. Notre Dame: University of Notre Dame Press, 2001.
. Feser. Scholastic Metaphysics. 212-213.
. Ibid. 213.
. Davies, Brian. The Reality of God and the Problem of Evil. New York: Continuum International Publishing Group, 2006. Print, 42-43.
. On this point, see especially Oderberg, David S. Real Essentialism. New York: Routledge, 2007. ebook.
.Feser, Edward. The Last Superstition: A Refutation of the New Atheism. South Bend: St. Augustine’s Press, 2008. ebook.
. Feser. Scholastic Metaphysics. 213.
. Ibid. 214.
. For more in depth discussion of this point, see Ibid. 71.
. Ellis, Brian. 2009. The Metaphysics of Scientific Realism (Montreal and Kingston: McGill-Queen’s University Press). 59. Quoted in Feser. Scholastic Metaphysics. 215.
. Feser. Scholastic Metaphysics. 215.
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