Can We Trust Our Senses?
In the 17th century, Rene Descartes (d. 1650 A.D.) published several works of philosophy that had a substantial effect on how people in Europe thought about our world, and importantly, about our capacity to understand it. Since the great thinkers of ancient Athens, people sought to understand our world from the belief that everything, living and non-living, is comprised of form and matter. In non-living things, the analysis is quite direct: inspecting what a thing is made of gives you the matter of its being, and the shape tells you what it does. Taken together, the form and matter of something tells you what it is. In living things, understanding them is more complicated, and interesting. The “form” of a living thing is its nature which is shared in common by individual members of each species. Thus, for example, there is a horse nature, a dog nature, a human nature, and each member of a species expresses the nature of its species. This process of expressing a living thing’s nature begins at conception when the internal power of a thing’s nature shapes the body through gestation into a form that expresses the animal’s nature. Aristotle (d. 322 B.C.) gives a fascinating account of how the human soul in gestation produces a body that is the perfect instrument for expressing intellect. Descartes argued that the form/matter distinction does not tell us about things with any kind of certainty because our senses can deceive us.
Descartes also contended that appeal to final ends in things tells us nothing useful about them. This is a crucial element in the turn from pre-modern to modern thought. The issue here had to do with a general frustration over the fact that the study of being as an exercise in philosophy had not yielded the kind of certainty in our knowledge of things that many people wanted. Final ends, importantly explained for us in the writings of Aristotle, tell us what is thing is for. The final end of a thing is what it exists to do. Something or someone is a composite of form and matter, but the coming together of form and matter is done for a purpose, and understanding the purpose, for each kind of thing, gives us a complete understanding of what it is and its place in the order of nature. Final ends, however, suggest a giver of ends, that is, a creator who made everything, including us, with a purpose in mind. The idea that Descartes and others in his time were developing is that they might gain the kind of certainty of knowledge they desired of things if they examined things only from a materialist perspective.
Descartes proposed a method for studying the world and the things in it by starting from doubt. I will doubt everything, Descartes declared, that I cannot explain “clearly and distinctly.” So, Descartes begins considering things from the starting place of doubt, looking for what cannot be doubted, by observing that he knows he exists, as a thinking thing, because he is thinking. (This is the famous cogito ergo sum, I think, therefore I am. But Descartes was scooped more than a millennium earlier by St. Augustine who wrote that when he has doubts about God, he knows for certain that he himself exists because he is doubting. It may not be a co-incidence that Descartes had studied the writings of Augustine.) There is an important theme here that may not be obvious at first observation, and that is the search for a method of studying the world around us that uses the data of sense perception but does not rely on them. The senses can mislead us. St. Augustine understood this, too, and responded by observing that sense perceptions do not come to us already interpreted. We must take judgements of the mind about our sense perceptions and in this way work out the various ways that perceptions, at first, can be confusing. So then, can we trust our senses, or must we “trust the science”?
It seems that thinking begins in sense experience. However, this observation does not entail the idea that we cannot reliably think about truths that go beyond the phenomena perceived by the senses since if this was true, we could not understand beauty or justice or truth or love. So, to say that thinking begins in sense experience is to observe that in order to think, one must think about something, and the something we think about comes to us initially through a sense experience. Imagine someone who is conceived in such an unhappy state that he has no functioning sense organs. Now, at forty years old, having never seen, heard, tasted, smelled, or felt the touch of anything, can he think? It is interesting to observe that when people are asked this question, there is a general hesitancy to say “no.” Most people when addressed with this question want to believe that such people can think, or anyway certainly can communicate with God. While we can desire that this be so, we cannot know it, so we are left with sense experience as the leading candidate for the starting place of thinking.
Can sense experiences be trusted? Our senses are wonderfully calibrated for understanding the world we live in, and this is the reason we can trust, for example, that what we see is there and is as we perceive it. As we just observed, however, sense perceptions as they first appear to us can be confusing or misleading. And, as we have observed, the mind is endowed with the gift of judgment. In the 4th century A.D., St. Augustine in North Africa observed that when one is on a lake in a boat and dips an oar into the water, the oar appears to bend where it enters the water. Of course, the oar doesn’t bend, as is clear when the oar is raised out of the water, and we know this, Augustine argues, because the mind takes the correct judgment that the water gives the appearance to the eye that the oar is bending when it is not. It is important to be clear that the claim that our senses can be trusted takes our sense perceptions to be reliable starting places for thinking about our world, but they are starting places from which reflection, analysis, and conversation proceed.
The journey from ancient and medieval thought to modern thought is more complex than simply rejecting final causes in nature, including human nature, but it has been very influential. This discussion began with the assertion that thinking begins in sense perception, but proceeded to say that this is where thinking begins, since we must reflect on the nature, meaning, and implications of those perceptions (and, though it’s outside the scope of argument here, the intuitions we have about things). Fundamental to how each of us thinks about our sense perceptions is worldview. One’s worldview is comprised of those suppositions one fundamentally believes, so that how one thinks about things is governed by the suppositions of one’s worldview. If someone believes that the earth and all life on it, including us, were created by God who loves us, that we are created in the image and likeness of God for communion with him, that we are given dominion over the earth and the life on it, and that the moral law is promulgated by God and discoverable by us, he will think differently than do people who insist there is no God, that life began spontaneously and evolved after that by random, unguided processes, and that morality is invented and differs from one person to another. Importantly, where disagreements are grounded in differences of worldview, they are often beyond resolution, and this is among the important reasons why loss of a coherent cultural tradition is a grievous thing. A people living in any place whatever who do not share a common worldview, but rather who are marked by differing, irreconcilable worldviews, have no common culture. (Why else do so many Marines and Sailors, from wherever in the country they are from, retire in Jacksonville?)
Science is a tool; it is a bundle of ways for examining our world in order better to understand it. It is not a thing that speaks to us in oracles, as in “trust the science.” In fact, the very admonition to “trust” the science flies in the face of the natural skepticism that should mark a mind thinking scientifically. The definite article, “the” science, suggests that there is a narrative of things, whatever they are, that the entity “science” has confirmed to be true. Thus our duty is simply to trust what science has determined to be true. Note, however, that this insistence to trust the science, or trust the experts, places people who trust the science in a delicate position because if on any topic “the science” is wrong, trusting people are believing falsehoods to be true. The problem here is that we each have a duty to think things through on our own as well as we can. This involves not just personal study or investigation, but also discussion with others, which over time develops not just understanding, which is important, but community also. Happily, these good things can be ours if we begin by trusting our senses.
