The Changing Faces of Reality

I. The Changing Character of Physical Reality

We live in a world of change, and nowhere is that more pronounced than in the sciences. Indeed, a textbook unrevised for two or three years is practically useless in most fields, and a laboratory with ten-year-old equipment is a museum. But most scientists are quick to point out that some things in science are far more secure—the periodic table, the laws of thermodynamics, relativity, the genetic code, biological evolution—and that we are steadily building a foundation of unchanging fact from which a clear picture of physical reality is emerging.

Not everyone agrees with this expectation, however, even within the scientific community. In fact, among the growing group of scientists interested in the philosophical implications of science, it has become apparent that we can no longer talk about scientific concepts and even mechanisms as though they were literal descriptions of objective reality.

A. NAIVE TO CRITICAL REALISM

In his book Intimations of Reality, Arthur Peacocke tells us that from about 1920 until 1970 science was viewed as an "essentially logical enterprise" through which the external world could be exhaustively described. Peacocke quotes Mary Hesse's version of the earlier view in Revolutions and Reconstructions in the Philosophy of Science:

Science is ideally a linguistic system in which true propositions are in one-to-one relation to facts, including facts that are not directly observed because they involve hidden entities or properties, or past events or far distant events. These hidden events are described in theories, and theories can be inferred from observation, that is, the hidden explanatory mechanism of the world can be discovered from what is open to observations. Man as scientist is regarded as standing apart from the world and able to experiment and theorize about it objectively and dispassionately.

Mary Hesse goes on to explain that the developments of the past two decades have made this description appear exceedingly naive. Indeed, every part of this account has been brought into question. A forerunner in this critique of science is Thomas Kuhn, whose Structure of Scientific Revolutions, published in 1970, proposed a new interpretation of the history of science. Kuhn argues that science goes through periods of normality during which accepted paradigms—broad conceptual frameworks—are employed and applied, and periods of revolution in which these paradigms are shattered, and replaced by new ones. The implications of this picture for our understanding of physical reality are far-reaching. If this be true of science, there seems little hope that the "hidden explanatory mechanisms of the world" can be discovered. A simple convergence to a unique scientific truth seems highly unlikely.

Following Kuhn, a new emphasis was placed on the sociological factors influencing the development of science, an analysis of which turned out to be as complicated as the scientists themselves. As Arthur Peacocke describes it:

Science came to be seen as a continuous social enterprise, and the rise and fall of theories and the use and replacement of concepts as involving a complex of personal, social, intellectual, and cultural interactions that often determined whether a theory was accepted or rejected. Theories are constructed, it was argued, in terms of the prevailing "world view" of the scientists involved: so to understand them one must understand the relevant world view. A new emphasis was therefore placed on the history of science, especially the sociological factors influencing its development. Thus a new area was opened up for the application of the expanding enterprise of the sociology of knowledge in general and of scientific knowledge in particular. However, it turns out that the "world view" of the scientist is an exceedingly complex and elusive entity—even more so when a community of scientists is involved.

Some sociologists of science concluded that the physical world has little to do with the conclusions arrived at by the scientific community. In essence, the products of science are social constructions like any other products of culture.

This extreme view finds many critics in and out of the scientific community. One of the most effective spokesmen for scientific reality is philosopher Ernan McMullin, who has argued for uniqueness in scientific truth gathering. He points out that even though science is a social product, the social factors are limited by the unique corrective character of scientific activity. The continuous filtering and sifting that go on in the course of experimental collaboration and scientific interaction and publication lead to a progressive elimination of distortion. McMullin has also commented on the "fertility" of scientific theories in further support of their realistic status. A good scientific theory in his view is able to predict novel phenomena and new directions. It has what he calls "logical resources." It also has another resource, a subtle capacity to suggest modifications when predictions fail, thereby providing a creative move for the scientist. In this respect McMullin compares the scientific theory or model with the poet's metaphor, which he describes as follows:

The poet uses a metaphor not just as decoration but as a means of expressing a complex thought. A good metaphor has its own sort of precision, as any poet will tell you. It can lead the mind in ways that literal language cannot. The poet who is developing a metaphor is led by suggestion, not by implication; the reader of the poem queries the metaphor and searches among its many resonances for the ones that seem best to bear insight. The simplistic "man is a wolf" examples of metaphor have misled philosophers into supposing that what is going on in metaphor is a comparison between two already partly understood things. The only challenge then would be to decide in what respect the analogy holds. In the more complex metaphors of modern poetry, something much more interesting is happening. The metaphor is helping to illuminate something that is not well understood in advance, perhaps, some aspect of human life that we find genuinely puzzling or frightening or mysterious. The manner in which such metaphors work is by tentative suggestion. The minds of poet and reader alike are actively engaged in creating.

The comparison of the creativity of scientific theory and poetic metaphor brings to mind the special contribution that scientist-philosopher Michael Polanyi has made to our appreciation of the belief system of the scientist. To raise the question of belief might seem to provide one more salient argument for the social scientists, but Polanyi's analysis arrives at the astounding conclusion that the scientist's commitment to the essential truth he is seeking actually serves as a valid and even essential component in approaching reality. The social context, at least at the personal level, actually ensures that the scientist is moving toward reality. Further discussion of this aspect can also be found in our book, The God Who Would Be Known.

The debates between extremists arguing for scientific reality as purely social construction and those arguing for science as final truth has led to a good compromise referred to as the critical realist position, which McMullin describes as follows:

The basic claim made by scientific realism ... is that the long-term success of a scientific theory gives reason to believe that something like the entities and structure postulated in the theory actually exist. There are four important qualifications built into this: (1) the theory must be a successful one over a significant period; (2) the explanatory success of the theory gives some reason, though not a conclusive warrant, to believe [it]; (3) what is believed is that the theoretical structures are something like the structures of the real; (4) no claim is made for a special, more basic, privileged, form of existence for the postulated entities.

According to Peacocke, the qualifications ("significant period," "some kind," "something like") built into this description are essential to a defense of scientific realism. Working scientists understand the extent and nature of provisionality that is assigned to theories in their field.

Their proposed theories and models are understood as no more than approximations of the structures of reality. Nevertheless, there is often an increasing sense of confidence that reality is being more and more accurately described, especially as that knowledge is successfully applied in prediction and control and in the design of new experiments. This description Peacocke refers to as "a skeptical and qualified realism."

To illustrate this approach to scientific realism, Peacocke takes the example of the electron. Scientists are committed to "believing in" the electron on the basis of much experimental data. However, "what they believe" about electrons has undergone many changes, but they still refer by way of long social links to the entity described in that historical event when the electron was first discovered. Physicists believe in the existence of electrons but are reluctant to say what they are. But "they are always open to new ways of thinking about them that will enhance the reliability of future predictions and render their understanding more comprehensive."

But what makes the electron most believable by the physicist is that it functions as a tool. Despite the fact that the electron cannot be observed, it can regularly be manipulated to investigate other aspects of nature. Peacocke calls this "the experimental argument for realism," pointing out that it deals with entities rather than theories. To illustrate the experimental argument, Peacocke quotes Ian Hacking in Representing and Intervening as follows:

There are surely innumerable entities and processes that humans will never know about. Perhaps there are many that in principle we can never know about. Reality is bigger than us. The best kinds of evidence for the reality of a postulated or inferred entity is that we can begin to measure it or otherwise understand its causal powers. The best evidence, in turn, that we have this kind of understanding is that we can set out, from scratch, to build machines that will work fairly reliably, taking advantage of this or that causal nexus. Hence, engineering, not theorizing, is the best proof of scientific realism about entities.

It should be noted that this argument points up a significant weakness in recent speculations by theoretical physicists in connection with the grand unified theories. These theories, which seek to bring the forces of the universe into a single coherent structure, are highly speculative and for the most part unsubstantiated by empirical data. There is here what physicist Richard Morris calls a "widening gap between theory and experiment" and a consequent "risk of putting forth questions that are unverifiable, and therefore meaningless."

B. SCIENTIFIC MODELS

Earlier we alluded to the way in which scientific theorizing and model building had its counterpart in the poet's metaphor. Arthur Peacocke tells us that, strictly speaking, the metaphor can only be a figure of speech, in which we speak of one thing in terms that suggest some other thing. On the other hand, a model need not be linguistic, though the two may be closely linked, since metaphors arise when we speak about our models. For example, the use of the computer as a model for the brain elicits the metaphors of "programming," "input," "feedback," and "memory."

As we have seen, the poet's metaphor helps to illuminate that which is not well understood by tentative suggestion, leaving the reader to create ideas and images from what is given in another more familiar form. The scientific model performs a similar function in that it generates metaphorical theoretical terms that suggest a network of explanation. Scientific theories are built by construction of models, and good models are not only inseparable from their theories, but allow for theory development by suggesting new possibilities and accommodating new observations. "A model," Janet Soskice says in her book Metaphor and Religious Language, "is the living part of the theory, the cutting edge of its projective capacity and, hence, ... indispensable for explanatory and predictive purposes."

Arthur Peacocke points out that there is not total agreement on the essential role of the model in scientific theorizing. Some scientists and philosophers regard models as helpful but carrying no commitment concerning their relation to reality. But the majority take a critical realist approach and see models as essential and permanent features of science. However, he points out that the critical realist sees the model as only a partial and incomplete expression of reality, a construction that no one would view as final truth. The use of complementary models in science, such as the wave and particle models for light in physics, should serve to remind us that models can never be literal and always contain some inadequacy.

In agreement with Peacocke, physicist Richard Morris, in his book The Nature of Reality, points out that by the end of the nineteenth century, physicists were viewing scientific theories as approximations that were only models of reality though sometimes very good ones. He comments: "Theories bore the same relation to the physical world that an architect's model did to a building, or that a detailed drawing did to a scene in nature. The correspondence between model and reality might be very close, but it could never be exact." But the reasons for the present conservative point of view on the part of most physicists stems from the fact that the entities that are studied are rarely seen directly and only inferred from various kinds of observed phenomena. One cannot see gravitational fields or the curvature of space-time, and even an electron must be inferred from the spot of light it leaves on a fluorescent screen or the track of tiny bubbles of hydrogen gas that a beam of electrons leaves in a bubble chamber.

The theoretical physicist devises theories about the behavior of these particles, but if theoretical predictions are subsequently confirmed by experiment, one still has not demonstrated their real existence. All that can be said is that the model conforms reasonably well to reality. It does not exclude the possibility of other models or other refinements of the present one. In fact, Morris says, in every field of physics there are experimental results that do not agree with theoretical predictions at all. Often these anomalous results are ignored and sometimes they later prove to be the result of faulty experimentation. However, occasionally they prove to be fundamental, explainable only when whole new theories are developed.

Despite this long history of revision and rebuilding of the models of physics, Morris tells us that some present-day scientists are suggesting that their models are approaching perfection, a point of view that was characteristic of the age of Isaac Newton, who thought it was possible to discover exact laws of nature. The current proposal of a theory of quantum gravity by Stephen Hawking as described in his book A Brief History of Time seeks to join the four forces of nature into a single unified theory. Hawking is so intrigued by the all-inclusiveness of the theory and its apparent capacity to explain the early stages of the origin of the universe that he equates quantum gravity with physical reality. This hope was expressed at the time of his inaugural lecture as Lucasian Professor of Mathematics at Cambridge in 1980; ironically, he was assuming the chair once occupied by Sir Isaac Newton.

Not everyone in physics is happy with Hawking's idea that a complete theory will be found. Morris goes on to explain that Freeman Dyson of Princeton's Institute for Advanced Study is one such dissenter. Dyson has commented: "If it should turn out that the whole of physical reality can be described by a finite set of equations, I would be very disappointed. I would feel that the Creator had been uncharacteristically lacking in imagination." Dyson goes on to say that it is more likely that the laws of physics are inexhaustible, basing his argument on the famous theorem of the Czech mathematician Kurt Gödel. Gödel's theorem, which was proved in 1931, states that it is not possible to demonstrate that any mathematical system is both consistent and complete. If the system is consistent, then it cannot be complete; there must exist true statements that cannot be proved within the system. Statements of this kind are referred to as undecidable and a number of them have been described. Most mathematicians agree that because of this limitation on mathematical systems—which could be viewed as mathematical models—Gödel proved that mathematics is inexhaustible. It might be said that its models will never be complete. Dyson concludes that because of Gödel's theorem, mathematics will always have "fresh ideas to discover," and he hopes that physics will prove to be just as inexhaustible.