Today professional athletes are almost always evaluated by “scientific,” i.e. statistical, measurements of success and value, but the old-fashioned “eye test” is sometimes still invoked. The eye test refers to one’s impression from actually watching an athlete or team compete, and its results sometimes contradict the armchair judgments of statisticians. Occasionally a player or team may look much better “on paper” than they do in real life—as might happen with a good player on a bad team or a good team in a bad conference—or, of course, vice versa.

The longstanding evolution debate has traditionally pitted proponents of science against proponents of religious belief, battle lines drawn by Darwin himself in his portrayal of evolutionary theory in The Origin of Species. Proponents of religious belief have been joined, moreover, by some noted philosophers (such as C. S. Lewis and Alvin Plantinga) in challenging the modern scientific monopoly on knowledge of the world.

Although science, religious belief, and philosophy are all vital sources of our knowledge of the world and our place in it, they are not in fact exhaustive sources. We also have yet another type of lens: our own two eyes. Before scientific inquiry, philosophical refinement, and even religious belief, the operation of our eyes and other senses first acquaints us with the world around us.

This most literal of lenses, corresponding with the “eye test,” posed a major stumbling block to Darwin’s arguments for his evolutionary theory both in The Origin of Species and in The Descent of Man. In these works, Darwin clearly struggled with the objection that his theory looked much better “on paper” than it did in real life.

Start your day with Public Discourse

Sign up and get our daily essays sent straight to your inbox.

This concern emerges first when we consider Darwin’s case for a universal “struggle for existence,” a concept foundational to his ideas of “natural selection” and “survival of the fittest.”  In Darwin’s vivid words,

We behold the face of nature bright with gladness, we often see superabundance of food; we do not see or we forget, that the birds which are idly singing around us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that, though food may be now superabundant, it is not so at all seasons of each recurring year.

In classic Debbie Downer style, one can picture Darwin casually ruining an unsuspecting bird-watcher’s day by reminding him that these birds are murderers whose children will be murdered in turn and who, even if they avoid this murderous cycle, will likely die of starvation at some point anyway.

Pessimism aside, though, Darwin is trying to accomplish something crucial and profound in this passage. He wants his reader to look past—or overlook—how we normally “behold the face of nature.”

Darwin is striving to undermine our first impressions of the world by labeling them merely superficial and even grossly misleading; the way the world looks to our ordinary senses is not only different from, but directly contrary to, the way the world actually is. We see peaceful beauty where there is actually ugly warfare. If we want to see the world accurately, we need to take off our natural rose-colored glasses. When it comes to evolution, Darwin argues, the “eye test” leads us astray.

Darwin’s most telling struggle with the “eye test” comes later in The Origin, in his treatment of—what else—the eye itself. Darwin opens a section titled “Organs of Extreme Perfection and Complication” with the following admission:

To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.

This absurdity, for Darwin, means that “it is indispensable that the reason should conquer the imagination,” and that his theory should overcome the apparent “common sense” of the matter.

At the same time, Darwin admits to feeling “the difficulty far too keenly to be surprised at others hesitating to extend the principle of natural selection to so startling a length.”

Darwin is clearly aware—and bothered by the fact—that his theory of evolution through natural selection is not only unsupported by, but actually contradicts, the reports given to us through our senses, as well as the “common sense” we gain from these reports over time. So he argues, in response, that this common sense is founded on mere “imagination” rather than “reason,” and with a Kantian determination he asks that we repress our “empirical” impressions in favor of our abstract theoretical convictions.

Yet why, we can ask, should we trust Darwin’s theory more than our own eyes? As persuasively as this theory explains many phenomena of nature and archeological discoveries, is its acceptance worth having to admit that the world is actually nothing like our experience of it? If a theory that the earth rests on the shell of a giant sea turtle explained enough phenomena, would it similarly command our assent?

Regardless of whether Darwin is right, the fact remains that we clearly see fixed and distinct species existing in ordered hierarchical beauty, not the fluid and formless continuity his theory depicts. As far as we know from direct observation and recorded history, trees seem to have always been trees, starfish to have always been starfish, squirrels to have always been squirrels, and human beings to have always been human beings. Species appear to have fixed and ordered relationships with one another and to fit together in a rational way, and not to lie on a disorganized continuum.

While this tension between Darwin’s theory and our experience may not be an insurmountable problem—indeed, science has discovered other truths that run more or less counter to common sense (such as the appearance of the sun traveling around the earth rather than vice versa)—it should be given more serious consideration than Darwin, or anyone since, has given it.

After all, some serious philosophers—most notably Aristotle, Aquinas, and Locke—think that all of our knowledge of the world comes initially through our senses. Our eyes and other senses, according to this line of thinking, tend to inform us rather than deceive us.

This is a most sensible (for lack of a better word) position, and remains more plausible than the skepticism Darwin’s theory requires. The assumption that we are ill-fitted to the world we seek to understand is just that, and one much less likely than its opposite. While our senses might not be infallible, there is little reason to think they are outright deceptive. And while we shouldn’t simply reject evolutionary theory because it contradicts our ordinary sensory experience of the world, we should also be wary of committing the opposite mistake.