Originally posted here.
Throughout the centuries the Christian tradition has had a love-hate relationship with Aristotle. His logic and metaphysical categories provided strong tools for developing and formalizing such classic doctrines as the Incarnation and the Holy Trinity. On the other hand, he famously held that the universe was eternal and that there was no first man such as Adam, putting him at odds with Christian belief. Yet in the midst of this conflict, there is much to be gathered and adopted by the Christian. Here I’d like to examine a few of Aristotle’s ideas about the essences of things and see how they relate to the Christian view of man.
The first thing to note is that humans, along with every other kind of thing, have “essences” or “natures”. An essence is simply that in virtue of which a thing is what it is. It’s what makes the definition of a thing true. It’s also the grounding of a thing’s essential properties, i.e. those properties which are intrinsic to that type of thing. Without essences we could not form inductive laws, we could not differentiate between kinds of things, and we couldn’t even properly define our concepts.
Essences entail that things have natural ends or functions (what Aristotle calls the “telos”). It would be incorrect to understand “function” in terms of the functions of human artifacts such as wheels or fishing rods. Rather, things have functions in the sense that they function in a certain natural way. So we can see clearly that by their very essences things like dogs or snakes have natural functions, including sensory perception, reproduction, self-change, and sustenance. This is what makes it good for them to pursue certain goals, like eating food or reproducing. To generalize, it is good for them to fulfill their functions.
This may seem irrelevant, but it has truly significant consequences for us as well. It gives medicine a normative structure, making sense of the strong and reasonable intuition that things such as broken bones or tumors are defects, while other things such as firmness of muscle or thorough digestion are indicators of health. It means that we all have certain functions which it is objectively good for us to fulfill. This can provide a foundation for objective morality and a guide to living our lives. Thus understood, essences are both indispensable and significant.
The Christian Picture:
So what is essential to humanity? Well, recall that essences are what differentiate things from entities of other kinds. In attempting to discover our essence then, it would be useful to see how we differ from other things. We share some characteristics with non-living things because we too are made of matter and have mass. But we are different from them precisely in virtue of the fact that we are alive. We are different from some living things like plants due to our sensory capabilities which we have in common with other animals. Yet we humans can be distinguished even from these creatures by our rationality. Unlike other animals, we can abstract from concrete particulars to general universal truths. Thus, humans are by their very essence rational animals.
How well does this fit into the Christian view of things? Consider the idea that God is a being with infinite knowledge, and thus an intellect. In Romans 11:33 for instance, Paul the Apostle praises God’s omniscience: ” O the depth of the riches of the wisdom and of the knowledge of God!” Aristotle’s view confirms precisely what the believer says, that is, that humans are by their very essence endowed with an intellect and will like God’s. As Genesis 1:27 says: “God created man to his own image: to the image of God he created him: male and female he created them.” Every human, male and female, is essentially made in God’s image.
We can also conclude from Aristotle’s view that, because humans have an essence with natural ends, there are some things that are objectively good for all of us, and that these objective moral truths are available to anyone who uses his or her reason and conscience. This confirms what we find in Romans 2:14-15: “For when the Gentiles, who have not the law, do by nature those things that are of the law; these, having not the law, are a law to themselves. Who show the work of the law written in their hearts, their conscience bearing witness to them.”
Much more could be said about all of these ideas. Yet it becomes clear how strongly these Aristotelian theses can be used to support what the Christian affirms. Hence, there is much fruit to be found by the Christian in the Aristotelian tradition, making the ancients very worthy of our attention.