Why science does not always have the right answer
Scientist Nigel Brush explores where science breaks down and why it cannot define absolute truth.
By Nigel Brush
(March 10, 2006)
In his recent book A World Without Time: The Forgotten Legacy of Gödel and Einstein, Palle Yourgrau argues that Albert Einstein, Kurt Gödel and Werner Heisenberg “were the authors of the three most fundamental scientific results of the [20th] century.” Each of these scientific results identified “profound and disturbing” limitations on what scientists could know about the physical universe.
The limitations identified by Einstein, Heisenberg and Gödel have profound scientific and philosophical implications that are still being absorbed by the scientific community. These discoveries also have significant religious implications that are relevant to the ongoing debate between science and Christianity. Perhaps the most important implication of these discoveries is that, given its limitations, scientific truth should not be equated with absolute truth.
Einstein’s theory of relativity undermined the absolute synchronicity of time by showing that the rate at which time passes is not fixed but depends on the motion of the timekeeper. During the Enlightenment, Pierre Simon, Marquis de Laplace, believed that scientists could determine the entire history of the
universe — both past and present — if they could calculate the position and velocity of every particle in the universe at a single point in time. Einstein, however, showed that Laplace’s idea was not only impractical but also impossible because there is no such thing as a single point in time for the entire universe. Time is relative.
Heisenberg’s uncertainty principle set a limit on our ability to simultaneously know both the position and momentum of subatomic particles. Because of the similarity in scale between subatomic particles and the energy we use to illuminate these particles, we change the behavior of particles whenever we attempt to observe them. Thus, it is not only impossible to know the position and velocity of every particle in the universe at a single point in time, it is impossible to simultaneously know the position and velocity of even one particle. These discoveries by Einstein and Heisenberg reveal that there are questions about nature that science simply cannot answer because of spatial barriers in both the macro- and micro-universe.
Scientific truth not absolute
Even without the work of Einstein and Heisenberg, it was already becoming apparent in the 20th century that scientific truth was not absolute. In the past, when ideas about the natural world might remain unchanged for centuries or even millennia, it was much easier to believe that such truths were absolute. However, as the pace of scientific research and discovery has continued to accelerate, the temporal character of scientific truth has become increasingly apparent. Major revolutions in scientific thinking have occurred throughout the 20th century: relativity and quantum mechanics in the 1920s, the expanding universe in the ’40s, plate tectonics in the ’60s, string theory and impact catastrophism in the ’80s. In such a dynamic intellectual environment where scientific knowledge grows exponentially, some of the scientific truths of today inevitably become the scientific falsehoods of tomorrow. Given the nature of the scientific method, however, such change should be expected. The point of scientific research is not to continually reaffirm what we already know. Rather, it is to break new ground, to gain new insights, to understand the workings of nature at new and deeper levels. Scientific truth has significant temporal limitations — its truths are not absolute — they continue to change.
One of the primary reasons science does not provide absolute, unchanging truth is a logical limitation within the scientific method itself. Founded on the principle of induction, the scientific method uses observations to create generalizations about nature. However, generalizations based on a finite number of observations can never be absolutely certain. The only way that empirically derived generalizations can be absolutely proven is by observing every specific instance subsumed under that generalization. This, of course, is impossible, so every inductively derived scientific generalization must — as philosopher Karl Popper said — remain forever tentative. A single negative instance can, in principle, invalidate a generalization based upon millions or even billions of observations. This is known as David Hume’s problem of induction and has been an interesting philosophical problem since the 1700s.
In the first half of the 20th century, advocates of logical positivism attempted to do an end run around the problem of induction by focusing on mathematical probabilities rather than absolute certainties. This attempt fell apart, however, when Gödel was able to show that all mathematical systems are themselves incomplete and inconsistent, that there is a difference between a true statement and a statement that has been proved within an axiomatic system. Gödel’s incompleteness theorem says that no consistent axiomatic system can exist that proves within that system every statement that is true about numbers, hence establishing a gap between what is provable and what is true. Scientific truth could not be made more secure by moving it from a logically limited foundation to a mathematically limited foundation. There is incompleteness inherent in any system of proof that limits what we can claim as a proven theorem in science.
Another limitation of science is human character. Scientists are not born as scientists. They are subject to the same formative childhood, teen and early adult experiences as their fellow nonscientists. After they become scientists, they are still part of their respective cultures and participate in the collective dreams, fears, interests and biases of their fellow humans. Therefore, the idea of complete scientific objectivity among the practitioners of the scientific method is an ideal rather than a reality. Scientists can endeavor to live up to the high standards of science but the end results sometimes fall short of the ideal. The Harvard paleontologist and essayist Stephen Jay Gould was fond of pointing out such inconsistencies in the lives of famous scientists, as he does here in The Mismeasure of Man:
I criticize the myth that science itself is an objective enterprise, done properly only when scientists can shuck the constraints of their culture and view the world as it really is … Rather, I believe that science must be understood as a social phenomenon, a gutsy, human enterprise, not the work of robots programmed to collect pure information. I also present this view as an upbeat for science, not as a gloomy epitaph for a noble hope sacrificed on the altar of human limitations.
Although modern science emphasizes the experimental approach, scientific experiments are often inconclusive. In their book, The Golem: What You Should Know about Science, Harry Collins and Trevor Pinch point out that when scientific experiments are inconclusive, scientists often resort to alternative methods of arriving at conclusions — the same methods used by nonscientists in everyday decision-making. Therefore, scientific truth is also subject to cultural limitations — scientists live and work within the ethos of their culture and time period.
Interpretation yields meaning
Finally, science is limited because of the very nature of the empirical observations on which the scientific method depends. Empirical observations may be far superior to idle speculations but they are no guarantee of absolute truth. Contrary to popular belief, facts do not speak for themselves. The empirical observation that a particular rock is red has little significance until we explain what that observation means, i.e., the rock is red because it’s hot or covered with blood or stained with iron or painted, etc. All empirical observations must be interpreted before they have any real meaning. Unfortunately, the preexisting beliefs, experiences and biases of the observer can play a significant role in determining how any particular empirical observation will be interpreted.
Although the number of possible interpretations for any particular observation is limited only by our imaginations, the truth of simple interpretations are far easier to empirically test than are more abstract interpretations. Consequently, as the level of abstraction and detail in a scientific theory increases, the level of agreement between scientists decreases. Thus, we sometimes see two scientists using the same body of data to arrive at totally different conclusions. This problem is particularly relevant to science and religion, where highly abstract interpretations are the usual focus of debate. Why is the highly abstract, metaphysical generalization, “There is no God; life and the universe arose by chance” any more scientific than the highly abstract, metaphysical generalization, “There is a God; life and the universe arose by the action of a creator”? Both statements are using empirical observations to justify highly abstract conclusions concerning the existence or nonexistence of God. Scientific truth has empirical limitations that are particularly evident when abstract interpretations are involved.
In light of these five limitations — spatial, temporal, logical, cultural, empirical — the great success of the scientific endeavor might seem surprising. Science, despite its limitations, is still a powerful tool. Nevertheless, in light of the limitations of science, scientists must be careful not to overstate their case.
Unfortunately, in the debate between science and religion, the superiority of scientific truth is usually taken for granted. Religion is shuttled to the sidelines and allowed to provide answers only to questions that science has little interest in answering — religion can discuss ethics and morality, or questions that science cannot presently answer — religion can try to fill in the gaps. On the other hand, science reserves for itself the right to speak authoritatively on all other matters. This domineering approach has, not surprisingly, generated resentment among many in the religious and philosophical communities.
Given its limitations, science cannot justify its claim to absolute supremacy in the human quest for truth. A little humility can go a long way toward resolving conflicts between individuals, cultures or disciplines. In its quest for truth, science cannot neglect the truth of its own limitations. Because of its limitations, scientific truth should not be equated with absolute truth.
Nigel Brush is an associate professor of geology at Ashland University in Ohio. His first book, The Limitations of Scientific Truth: Why Science Can't Answer Life's Ultimate Questions was published in November.
