Carroll Quigley - The Evolution of Civilizations

These rules about the nature of scientific hypothesis are so important that science would perish if they were not observed. This has already happened in the past. During the period 600-400 B.C. in the Greek-speaking world, the Ionian scientists applied these rules about scientific hypothesis by assuming that the heavens and the earth were made of (he same substance and obeyed the same laws and that man was part of nature. The enemies of science about the year 400 B.C. made assumptions quite different from those of the Ionians; namely, that the heavens were made of a substance different from those on earth and, accordingly, obeyed different laws, and, furthermore, that man was not part of nature (since he was a spiritual being). They accepted the older idea that the earth was made up of four elements (earth, water, air, fire), but assumed that the heavens were made of a quite different fifth element, quintessence. They admitted that the earth was changeable but insisted that the celestial areas were rigidly unchanging. They claimed that the laws of motion in the two were quite different, objects on the earth moving naturally in straight lines at decreasing velocity to their natural condition of rest, while objects in the heavens moved in perfect circles at constant speed as their natural condition. These nonscientific assumptions, made about 400 B.C. without proof and by violating the fundamental rules of scientific method, set up a nonscientific world view which could not be disproved. The Pythagorean rationalists were able to do this and to destroy science because the scientists of that day, like many scientists of today, had no clear idea of scientific method and were therefore in no position to defend it. Even today few scientists and perhaps even fewer nonscientists realize that science is a method and nothing else. Even in books pretending to be authoritative, we are told that science is a body of knowledge or that science is certain areas of study. It is neither of these. Science clearly could be a body of knowledge only if we were willing to use the name for something that is constantly changing. From week to week, even from day to day, the body of knowledge to which we attribute the name science is changing, the beliefs of one day being, sooner or later, abandoned for quite different beliefs.

Closely related to the erroneous idea that science is a body of knowledge is the equally erroneous idea that scientific theories are true. One example of this belief is the idea that such theories begin as hypotheses and somehow are "proved" and become "laws." There is no way in which any scientific theory could be proved, and as a result such theories always remain hypotheses. The fact that such theories "work" and permit us to manipulate and even transform the physical world is no proof that these theories are true. Many theories that were clearly untrue have "worked" and continue to work for long periods. The belief that the world is a flat surface did not prevent men from moving about on its surface successfully. The acceptance of "Aristotelian" beliefs about falling bodies did not keep people from dealing with such bodies, and doing so with considerable success. Men could have played baseball on a flat world under Aristotle's laws and still pitched curves and hit home runs with as much skill as they do today. Eventually, to be sure, erroneous theories will fail to work and their falseness will be revealed, but it may take a very long time for this to happen, especially if men continue to operate in the limited areas in which the erroneous theories were formulated.

Thus scientific theories must be recognized as hypotheses and as subjective human creationsno matter how long they remain unrefuted. Failure to recognize this helped to kill ancient science in the days of the Greeks. At that time the chief enemies of science were the rationalists. These men, with all the prestige of Pythagoras and Plato behind them, argued that the human senses are not dependable but are erroneous and misleading and that, accordingly, the truth must be sought without using the senses and observation, and by the use of reason and logic alone. The scientists of the day were trying to reduce the complexity of innumerable observed qualities to the simplicity of quantitative differences of a few fundamental elements. This is, of course, exactly what scientists have always done, seeking to explain the subjective complexity of qualitative differences, such as temperature, color, texture, and hardness, in quantitative terms. But in doing this they introduced a dichotomy between "appearance" and "reality" that became one of the fundamental categories of ancient intellectual controversy. All things, as the scientists said, may be made up of different proportions of the four basic elements—earth, water, air, fire—but they certainly do not appear to be. The same problem arises in our own day when scientists tell us that the most solid piece of rock or metal is very largely made up of empty space between minute electrical charges.

The Pythagoreans argued that if things are really not what they seem, our senses are at fault because they reveal to us the appearance (which is not true) rather than the reality (which is true). This being so, the senses are undependable and erroneous and should not be used by us to determine the nature of reality; instead we should use the same reason and logic that showed us that reality was not like the appearance of things. It was this recourse to rational processes independent of observation that led the ancient rationalists to assume the theories violating Occam's razor that became established as "Aristotelian" and dominated men's ideas of the universe until, almost two thousand years later, they were refuted by Galileo and others who reestablished observation and Occam's razor in scientific procedure.

The third part of scientific method is testing the hypothesis. This can be done in three ways: (a) by checking back, (b) by foretelling new observations, and (c) by experimentation with controls. Of these the first two are simple enough. We check back by examining all the evidence used in formulating the hypothesis to make sure that the hypothesis can explain each observation.

A second kind of test, which is much more convincing, is to use the hypothesis to foretell new observations. If a theory of the solar system allows us, as Newton's did, to predict the exact time and place for a future eclipse of the sun, or if the theory makes it possible for us to calculate the size and position of an unknown planet that is subsequently found through the telescope, we may regard our hypotheses as greatly strengthened.

The third type of test of a hypothesis, experimentation with controls, is somewhat more complicated. If a man had a virus he believed to be the cause of some disease, he might test it by injecting some of it into the members of a group. Even if each person who had been injected came down with the disease, the experiment would not be a scientific one and would prove nothing. The persons injected could have been exposed to another common source of infection, and the injection might have had nothing to do with the disease. In order to have a scientific experiment, we must not inject every member of the group but only every other member, keeping the uninjected alternate members under identical conditions except for the fact that they have not been injected with the virus. The injected members we call the experimental group; the uninjected persons we call the control group. If all other conditions are the same for both groups, and the injected experimental group contract the disease while the control group do not, we have fairly certain evidence that the virus causes the disease. Notice that the conditions of the control group and the experimental group are the same except for one factor that is different (the injection), a fact allowing us to attribute any difference in final result to the one factor that is different.