More About Function

In my book and other writings I have appealed to the notion of function to explain how we can achieve a degree of satisfaction or fulfillment in our lives. Taking “function” to mean what we are good at or good for, I claim that doing our function well is key to our flourishing and is accompanied by a feeling of well-being. On a personal, idiosyncratic level, if you are good at sports but not math, you will be better off pursuing a career, or at least a hobby, in the former rather than the latter. On a generic level applicable to all humans, if we can figure out what human beings in general are good for or good at, we can have a happy life by developing and exercising those abilities. As Aristotle says,

[A clearer account of happiness] might perhaps be given, if we could first ascertain the function of man. For just as for a flute-player, a sculptor, or an artist, and, in general, for all things that have a function or activity, the good and the ‘well’ is thought to reside in the function, so would it seem to be for man, if he has a function.(1)

In this essay I examine more carefully just what the notion of function entails, summarizing some of the recent philosophical research on the topic.(2) The Greek word ergon in Plato and Aristotle, translated as “function” or “work”, means what something does or what it is there for(3), what good it does.(4) Modern analysis gives us more detail. Just as our understanding of physics has gone well beyond Aristotle, so has our understanding of what function really is.

First, note that there are two kinds of function, biological and instrumental. Biological functions are things such as these: the function of the heart is to pump blood; the function of the eye is to see; legs and feet function to enable an organism to stand and move around; the function of a polar bear’s white fur is to provide warmth and camouflage in snow. In all these cases the function of the part contributes to the ongoing life and health of a living being.

Instrumental functions pertain to artifacts and involve a deliberate purpose. For instance, the function of a telephone is to enable people to talk to each other over long distances. The purpose of talking could be many things, such as making an appointment or finding out information or just chatting. The purpose of doing those things is to contribute to the ongoing life of a human being.

In both cases we end up with a contribution to life, but in the biological case the contribution is direct and need not involve deliberate purpose, whereas in the instrumental case the contribution is indirect and does involve deliberate purpose. The modern analysis attempts to find parallels between these two kinds of function.

In both cases a thing’s function is a subset of what it does. A heart does a number of things: it pumps blood, it makes a sort of thumping noise, it makes squiggly lines on an electrocardiogram. Why do we say that its function is to pump blood, but not to make noise? Because pumping blood contributes to the health of the animal, but making noise is just a byproduct. If there were a silent organ that pumped blood, it would be a heart; but if there were a noisy organ that sort of looked like a heart but did not pump blood, it would not.

Similarly, a telephone does more than one thing: it enables people to talk to each other over a distance, it holds down papers when placed on top of them, it annoys people when it rings in a library, and so forth. Why do we say that its function is to enable communication and not to make noise? Because enabling long-distance communication is what the artifact is designed to do. A silent artifact that enabled us to talk to each other over a distance would count as a telephone, but a thing that rings but doesn’t connect distant people for talking would not.

As you can see, the contribution of an organ to the health of its host animal is analogous to the contribution of an artifact to the purpose of the structure in which it is placed. Both are embedded in larger systems. A heart is one organ among many in an animal; a single telephone is one device among many in a communications network. The heart, when it functions well, keeps the animal alive; the telephone, when it works, enables the communications network to fulfill the purpose for which it was designed. In both cases the entity in question is good for something within a larger context.

But what something is good for is not in itself enough to call it a function. A heart is a good source of nutrients for someone (or something) who eats it, but that’s not the function it evolved to serve. If we just consider hearts in the abstract, we would not say that their function is to provide trace minerals and B vitamins to those who consume them, but to pump blood. A telephone might be good for acting as a paperweight, but that is not its function, or at least not the function it was designed for. If we just consider telephones in the abstract, we would not say that their function is to be paperweights, but to be communication devices.

In both cases, how something came to be is part of what we mean by “function.” The heart came to do what it does by means of evolution through natural selection. The telephone came to do what it does by means of deliberate design and manufacture. We can say that hearts exist because they pump blood, and they pump blood because they evolved to do so. (More precisely: because doing so caused the proliferation of ancestors of animals containing hearts.) We can say that telephones exist because they enable long-distance communication by voice, and they enable such communication because someone designed them to do so.

Philosophers have sparred about whether an organ can be said to have a function because it contributes to the well-being of a present-time organism or only because it contributed to the reproductive success of that organism’s ancestors. I think the distinction is a bit trivial because the present-time organism has the potential to be an ancestor of future organisms, and the traits that contribute to its well-being also contributed to that of its ancestors. In either case, contribution to the success of the larger system of which it is part is crucial. The organ replicates through generations because it contributes to the well-being—in evolutionary terms, the fitness—of the organism of which it is a part.

To sum up the discussion so far, the concept of biological function is exactly parallel to that of instrumental function.

Here is the biological account:

  • An element has a function if it contributes in some way to the ongoing health, operation or maintenance of the organism of which it is a part; and
  • It came about through a process of natural selection such that its operation gave a selectional advantage to the organism’s ancestors.

Here is the instrumental account:

  • An element has a function if it contributes in some way to the ongoing operation or maintenance of the artifact or system of artifacts of which it is a part; and
  • It came about by deliberate design.

Now, to return to the original question, we can ask what the functions of the human being are. I focus on the biological account because I don’t consider humans to be artifacts (although some theists might disagree). The modern concept of function goes beyond the ancient Greek idea of what work (ergon) something does, and now the reason why good functioning leads to well-being is clearer. If an organ functions well, it contributes to the functioning of the whole, which in turn nourishes the organ. But does it make sense to consider humans to be organs in some larger whole?

That’s a profound question. Before we attempt an answer, let’s remember that humans are, obviously, living beings. In order to have any effect at all on whatever larger system we might find ourselves in, we have to be alive. Aristotle distinguishes three ways beings can be alive. He calls ways of being alive “soul’ (psyche). Aristotle contrasts the human way of being alive with two others, that of plants and that of non-human animals. Plants, animals and humans are all alive. All have soul; not a soul, but soul in general; we can call it soulness. Soulness in plants enables them to take in nutrients, grow and reproduce. Soulness in animals enables them to do those things and, in addition, to perceive their world and in most cases move around. The soulness of humans is that humans do all that plants and animals do and even more. Humans have in addition, according to Aristotle, the power to think rationally.(5)

The connection between functioning well and well-being is clear. A plant that absorbs nutrients well does better than one that absorbs nutrients poorly; that is, it has a better chance of surviving, thriving and reproducing. An animal that perceives its world and gets around in it well has a better chance of surviving, thriving and reproducing than one that does those things poorly. And human beings who think well have a better chance of surviving and thriving (for humans, reproducing is optional) than those who think poorly.

But humans do lots of things besides think. We can ride bicycles, play Frisbee, watch TV, argue with each other and do many other things. Which ones shall we look at to find out how to lead a fulfilling life? Plato says that a thing’s function is what only it does or what it does better than anything else.(6) Even so, there are quite a few things that humans do that other animals don’t do at all or don’t do as well. An Internet search for what makes humans special yields these and more:

  • We think symbolically and abstractly about objects, principles, and ideas that are not physically present.
  • We use language to communicate complex concepts and to coordinate social roles and group activities.
  • We have rich culture. We can transmit and replicate ideas, symbols and practices very quickly through writing, speech, gestures and rituals.
  • We cooperate in large, well-organized groups and employ a complex morality that relies on reputation and punishment.
  • We can understand what others are thinking and mentally take their point of view. We can intuit what another person is thinking so that we can both work together toward a shared goal.
  • We make tools of far greater complexity than the simple ones that apes, dolphins, birds and other animals use.
  • We create art and music.
  • We can pay attention to ourselves and think about our own thinking. This capacity is what I call second-order thinking, also known as meta-cognition and self-awareness. It is the foundation of our freedom to make choices and form our own destiny.

These are all functions in Plato’s sense; they are unique capacities that humans have. Arguably, doing any of them well enhances our ability to flourish and enjoy a sense of well-being. But what of the more recent understanding of function. Are humans anything like organs existing in a more comprehensive organism? If so, in what way do we contribute to the ongoing health, operation or maintenance of that organism?

Perhaps “organism” is too grandiose a term, being more metaphorical than literal, but it is undeniable that we exist and function within larger systems. We are embedded in nature; our role as creatures within a bioregion is quite analogous to that of organs within an organism. In addition, we are embedded in social systems: families, tribes, neighborhoods, cities, nations, clubs, religious assemblies, professional organizations, economic enterprises, political parties, sports teams and many more. Being with others is not optional for us; we must have ongoing and extensive contact with our fellows in order to survive and thrive.

Within these systems, our role is unique. Unlike nonhuman animals, we can choose our function. That is, we can choose whether and in what way our effects on the systems in which we are embedded enhance those systems. We can impose instrumental function on our biological and social foundations.

For example, in the natural realm a skillful homesteader can design and maintain a local ecosystem to be healthy and provide nourishment and benefit to its caretaker and to the plants and animals within it. My Permaculture teacher says the functions of humans (Permaculture calls them “services”) are to plan, to design and to haul around large amounts of stuff. But if the homesteader is not skillful, the ecosystem is likely to decline. In the larger ecosystem of our entire planet, we can collectively choose whether to take action to avert climate disaster or to stand back and let it get worse.

In social settings, there are numerous ways we can work for the greater good of our group or community and thereby increase our own well-being. We can volunteer to help out, we can take on leadership, we can be loving and kind to our neighbors, we can advocate for good policies, we can provide useful services, we can just smile and be friendly. Or not; it is up to us.

Plato says that the human soul’s function is deliberating, managing and ruling.(7) In other words, our function, if we choose to accept it, is to be stewards of our natural and social environment. But we can also ignore that opportunity. The potential for exercising a useful function is there, but it is up to us whether to actualize it. We can use our vast intelligence to function as stewards and take charge of the world in which we find ourselves situated. If we choose to exercise that function well, we flourish; if not, we don’t. The choice is ours.


(1) Aristotle, Nichomachean Ethics, I.7, 1097b 22-29.

(2) See Buller, Cummins, Millikan, Neander, Sober and Wright. In the years since Wright’s influential analysis in 1973 something approaching a consensus has emerged among analytic philosophers as to the meaning of the term “function.” As philosophers do, they have quibbled with each other about minor points, but the broad outline is clear. I am grateful to Professors Sinan Dogramaci and Ray Buchanan of the University of Texas at Austin for allowing me to sit in on their 2018 seminar on telos, function and explanation, where I was introduced to these thinkers.

(3) Wright, “Functions,” p. 146.

(4) Foot, Natural Goodness, p. 32.

(5) Aristotle, On The Soul, 2-3, 413a 20 – 415a 10.

(6) Plato, The Republic, 353a.

(7) Plato, The Republic, 353d.


Aristotle. Nichomachean Ethics. Tr. W.D. Ross. Introduction to Aristotle, Ed. Richard McKeon. New York: Random House Modern Library, 1947. Available online at

Aristotle. On the Soul. Tr. J.A. Smith. Introduction to Aristotle, Ed. Richard McKeon. New York: Random House Modern Library, 1947. Available online at

Buller, David J. “Introduction: Natural Teleology.” In Buller, David J., ed. Function, Selection and Design. Albany, New York: SUNY Press, 1999, pp. 1-27.

Cummins, Robert. “Functional Analysis.” The Journal of Philosophy, Vol. 72, No. 20. (Nov. 20, 1975), pp. 741-765. Online publication as of 17 August 2007.

Foot, Phillippa. Natural Goodness. Oxford: Oxford University Press, 2001.

Millikan, Ruth Garrett. “Proper Functions.” In Buller, David J., ed. Function, Selection and Design. Albany, New York: SUNY Press, 1999, pp. 85-95.

Neander, Karen. “The teleological notion of ‘function'”. Australasian Journal of Philosophy, Volume 69 Number 4, December 1991, pp. 454-468. Online publication as of 12 January 2018.

Plato. The Republic. Tr. Paul Shorey. The Collected Dialogues of Plato. Ed. Edith Hamilton and Huntington Cairns. New York: Pantheon Books, 1963.

Sober, Elliott. Philosophy of Biology, Second Edition. Boulder Colorado: Westview Press, 2000, pp. 86-88.

Wright, Larry. “Functions.” The Philosophical Review, Vol. 82, No. 2 (Apr., 1973), pp. 139-168. Online publication as of 22 May 2012.

How To Be An Excellent Human

Mysticism, Evolutionary Psychology and the Good Life by Bill Beacham, Ph.D.

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