The Limits of Science

Sometime ago I stumbled across a paper titled The Principal Elements of the Nature of Science: Dispelling the Myths by William F. McComas. One of the greatest problems facing modern science is that few people have taken the time to understand the nature of scientific knowledge. Individuals, the popular media, and even some scientists approach science with false expectations about what science can and cannot tell us. Christians can be some of the worst offenders in this regard. There is a lot of conflict which Christians have with science which could be eliminated if we had a correct philosophy of science. This is where McComas’s paper is helpful. He writes to dispel many of the myths which exist in regards to scientific knowledge and discoveries. His primary audience is science educators, but his observations are helpful to anyone who wants to think about science. What follows are reflections on the paper intermixed with my own thoughts about the nature of science.

The first myth that McComas deals with is that there is a progression in certainty which moves from hypothesis, to theories, to laws. This myth says that hypothesis are the least certain while laws are the most. McComas says that theories and laws are actually different kinds of knowledge. “Laws are generalizations, principles or patterns in nature and theories are the explanations of those generalizations.” (2) He uses gravity as an example. Newton was able to formulate laws of gravity. These laws simply describe what happens in nature when an object falls to earth. The theory, why gravity to works, was a question Newton could not answer. One of my favorite scientific “laws” when I was younger was that if you mix vinegar and baking soda, they produce a rapid, expanding reaction. Only later did I understand the theory, that acetic acid and sodium bicarbonate exchange atoms to form, among other things, carbon dioxide gas.

Scientific laws and theories are based on probability not certainty. Scientists observe phenomena and look for patterns. Whenever I let go of an apple in midair, it falls to the ground if nothing else restrains it. Thus a law of gravity can be formed. But just because something happens many times, does not make it necessary that it will happen again. Say I took a regular quarter and tossed it a thousand times and each time it landed heads up. After that I might make a law which says that this particular coin will always lands on heads. Of course, there is a chance, as small at it is, that the thousand and first time I toss the coin it will land tails up. To make the law more certain I will repeat the experiment. The probability of my law will increase, enough to were I would be willing to bet money on the outcome of a coin toss, but 100% certainty is impossible. Likewise, just because an apple falls to the ground every time I drop it, does not make it necessary that the next time I drop an apple it will fall. The probability that gravity will cease to operate as it has in the past is astronomically slim, but always possible.

One of the consequences of this is that all scientific knowledge is tentative. Few laws are as probable as gravity. Someone may come along and propose a better explanation for a phenomena or a more comprehensive mathematical equation. Laws become more difficult to make the more complex a subject is and the more variables that are present. Human beings are fantastically complex and there are innumerable forces which influence us. This is why research about dieting is so constantly being “overturned.” By its nature, such research is more tentative than other fields of scientific knowledge. However, because it is science, popular culture often attributes to it more certainty than it deserves.

Even something as firm as gravity is subject to change. The theory of gravity was explained during the Classical and Medieval periods by the fact that all objects are drawn to that which they are most like. Each of the four elements was drawn to its own kind. An apple fell to the ground because there was more earth in it than any other element. Air rose to the sphere of air which surrounded the earth and fire towards the sphere of fire which surrounded that. After Newton, gravity was explained (the theory) as the result of forces of attraction between objects. These forces were said to act (the law) proportional to the product of their masses and inversely proportional to the square of the distance between them. Einstein didn’t like this theory because gravity acts instantaneously, implying that attractive forces were moving faster than the speed of light. According to Einstein, nothing moves faster than the speed of light. For this reason he proposed the theory of general relativity. In his theory objects bend the fabric of space-time, like if you placed a bowling ball on a trampoline with a bunch of marbles. All the marbles would roll towards the more massive bowling ball. Scientific understanding is constantly moving.

One might say our scientific understanding is like a map. A map is not reality. It is only a person’s representation of reality at a particular point in time. Atoms used to be displayed in textbooks as a cluster of little balls with another little ball or balls in a consistent orbit around them. Such a picture was and is helpful to learning and discussion but it is not reality. More accurate understandings and diagrams of an atom have been developed, but they are still only models of reality, not the real thing.

Science is only as good as our senses and instruments. Take ultraviolet light for example. Because of its wavelengths our eyes are not able to perceive it. (Bees can see ultraviolet light. Many flowers have patterns visible only to creatures which can see ultraviolet light.) We shouldn’t disbelieve in the existence of ultraviolet light just because we cannot see it. In fact, we only know of its existence because we have instruments which enable us to detect it. Saying before the invention of these instruments that ultraviolet light doesn’t exist would be like declaring that there are no fish in a pond because you didn’t catch any. Maybe you were using the wrong bait. Most people believe that love exists even though one cannot hold love in a test tube. Science cannot put God under a microscope. Therefore, it is unable to prove or disprove the existence of God. Science cannot see what it cannot see. That is why we have disciplines like philosophy, metaphysics, and theology which we can use alongside of science to investigate the world.

All this means that there are questions that science can’t answer. McComas gives the example of abortion, “Science cannot answer the moral and ethical questions engendered by the matter of abortion….Science simply cannot answer moral, ethical, aesthetic, social and metaphysical questions, although it can provide some insights that might be illuminating.” (10) Science can tell us that at fertilization a zygote is formed with a genetic code that as a whole is different from the genetic information of the egg and sperm that formed it. What science cannot tell us is whether or not this zygote is a person. Neither can it tell us whether or not that person has a right to life. Science is only one of many voices at the table.

Scholar Jerry Root has a particularly good illustration of the nature of scientific knowledge. Science, he says, can tell us why a kettle boils. It can’t tell us, “Because I wanted a cup of tea and would you like one too.” Science has an amazing ability to tell us how something occurs, how heat causes water to boil. It can help us to boil water more efficiently. What it can’t tell us is why the water in the kettle is being boiled, its purpose or its origin.

Before I end this post, I want to include one last thought from the article in a slightly different vein from the rest. McComas comments on the importance of imagination and creativity in science. Imagination has always played a role in science, from the thought-experiments used by scientists like Albert Einstein to the snake dream of August Kekulé, which helped him theorize about the shape of the benzene molecule.

Unfortunately, many common science teaching orientations and methods serve to work against the creative element in science. The majority of laboratory exercises, for instance, are verification activities. The teacher discusses what is going to happen in the laboratory, the manual provides step-by-step directions and the student is expected to arrive at a particular answer. Not only is this approach the
antithesis of the way in which science actually operates, but such a portrayal must seem dry, clinical and uninteresting to many students. In her 1990 book, They’re Not Dumb, They’re Different, Tobias argues that many capable and clever students reject science as a career because they are not given opportunities to see it as an exciting and creative pursuit. The moral in Tobias’ thesis is that science may be impoverished when students who feel a need for a creative outlet eliminate it as a potential career because of the way it is taught.  (8-9)


One comment

  1. tolde by the weye · September 19, 2013

    Nice post, love the Jerry Root quote: Science can tell us why a kettle boils. It can’t tell us, “Because I wanted a cup of tea and would you like one too?” – I may have found a new e-mail signature. thanks@!

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