Commentary Magazine


Evolution and Dr. Sagan

To the Editor:

One who criticizes Carl Sagan’s scientific ideas should himself be better grounded in science than is Jeffrey Marsh when he takes Sagan to task for saying that evolution is a fact [“The Universe and Dr. Sagan,” May]. Mr. Marsh is wrong on several counts.

First, where is it written in letters of fire that “the main characteristic of a fact is that it be directly observable”? A solid fact may often be established by inference, with direct observation not involved. Would Mr. Marsh accept it as a fact that he has a brain? Yet unless he has had his skull opened, or perhaps has had a cranial X-ray, his brain has never been observed directly. The existence of a brain inside his cranium is inferred from his possession of numerous other human—or vertebrate, or chordate—characteristics. Since he belongs to these categories, it is a solid fact that he has a brain.

Second, evolution is not a “hypothesized series of events” that occurred in the dim past when no intelligent observers were around. Evolution is occurring right now, and there is direct evidence to this effect. The average life of a species is about ten million years. Human history goes back only ten thousand years. Yet in this brief span—indeed, even in the last few years—there is direct evidence of the appearance or evolution of various new species. They include all cultivated species of wheat and corn; a species of Spartina, an English marsh grass; Malheurensis, a new species of wire lettuce discovered recently in Oregon; and triticale, a new species of grain artificially produced by hybridizing wheat and barley. New forms of bacteria are produced almost at will in the laboratory.

Mr. Marsh’s “concept” of evolution is actually two concepts. The fact of evolution, namely, that evolution occurs, is universally accepted by all competent and knowledgeable biologists and geologists. The theory of evolution, that is, the mechanism by which the process takes place, is much in dispute. The present sharp controversy is between the gradualists or neo-Darwinians and the punctuationists. Without question, both schools agree in accepting the fact of evolution as thoroughly verified. . . .

Stanley L. Weinberg
Ottumwa, Iowa

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To the Editor:

In his article, Jeffrey Marsh asserts that “. . . the main property of a fact is that it be directly observable. . . .” Mr. Marsh’s assertion is based on a Euclidean-Newtonian conception of a fact which since the advent of quantum theory and the principle of indeterminacy is not a scientifically tenable assertion. A fact no longer need be directly observable to be a fact. It is also a fact if it is indirectly observable through a constancy of statistically discernible manifestations. Thus, under the revolutionary impact of quantum theory and the principle of indeterminacy, a fact requires—just as in the case of the wave behavior of matter—a definitional duality: its main property can be that it is directly observable or that it is indirectly (statistically) observable. . . .

Some of the issues that remain to be resolved in evolutionary theory notwithstanding, its general validity is at the present beyond serious questioning. Or is it Mr. Marsh’s contention that the man of today is the same sociobiological man of, let’s say, one million years ago? What else would Mr. Marsh call the difference between the two but an evolutionary fact directly and indirectly observable by physical and cultural anthropology as well as biology?

I do agree with Mr. Marsh’s line of criticism of Sagan’s popular presentation of various aspects of science mainly because at times that presentation tends to fuse scientific speculation with scientific fact. But I totally disagree with his . . . statement that “the concept of evolution refers to a hypothesized series of events which by definition occurred at a time when there were no intelligent observers around,” and that because of this Sagan’s “assertion” that “evolution is a fact, not a theory . . . is obviously false.” Here Mr. Marsh confuses one of the working hypotheses of evolutionary theory with its main didactic thesis which is the study of the gradual process of sociobiological development usually—but not necessarily—in a gradual manner from simpler forms to more complex forms. I do not think that it is necessary for me to go into the details of the evidence available supporting that process of development other than to remind Mr. Marsh of the thoroughly evidenced fact of the growth of the human brain during approximately the last three million years to its present size and complexity.

In synthesis, then, it can be reasonably said that evolution is a fact in its general aspect, but that contrary to Carl Sagan’s assertion it is still theoretical in many of its particular aspects. . . .

D. A. Dominguez
New York City

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To the Editor:

Jeffrey Marsh assembles an extensive catalogue of charges against Carl Sagan. . . . To cite but one: Sagan is charged with the “absurd” claim that scientific advance requires thoroughgoing materialism, including the belief that the salvation of the world requires adopting the material view on a global basis. . . . Mr. Marsh then cites distinguished contributions to the advancement of science by Orthodox rabbis and Jesuit priests on the one hand and scientists like Newton and Kepler with profoundly religious views on the other. He thus implies that there is no necessary incompatibility between science and religion. Had he demonstrated in either or both instances that religious conviction was associated with scientific discoveries, he would have had a major argument. In fact, what he has demonstrated is an apparently limitless capacity among human beings for operating with non-intersecting categories of belief rigorously kept separate. Newton, Kepler, the Orthodox rabbis, and the Jesuit priests strictly adhered to the perspectives, criteria, and methods of science in dealing with scientific problems but reserved the religious perspective for other classes of problems. . . .

Mr. Marsh levels many other charges but the heart of his attack, his ultimate charge, is that Sagan “fail[s] to come to grips with the significance of religion.” . . . Sagan, it turns out, is not the object of Mr. Marsh’s attack; he is merely typical of the orientation of scientists. . . . Mr. Marsh evidently cannot accept the scientific view that chance factors account for the origin of the universe and of biological life, including human life; that evolutionary development converts simple life forms arising by chance into complex forms; and especially that life has no preexisting meaning but only the meaning generated and defined by human intelligence and will.

Mr. Marsh’s position has it that the universe is the creation of God; its orderliness the sign of the characteristics with which He endowed it; and that creation continues in the personal relationship God has with the inhabitants of the earth. There is no doubt whatever that he knows the basis for the scientific view, but his profound commitment to religion makes it unacceptable to him and obliges him to seek some reconciliation between science and religion which may be what he means by coming to grips with the significance of religion. If that is his intent, conscious or not, he has failed in two ways; first, for not acknowledging the issue and, second, for not giving some possible common ground or an indication of one between science and religion.

Walter Rosenauer
Jackson, New Jersey

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To the Editor:

Jeffrey Marsh’s critique of the ideas of Carl Sagan is thorough and thought-provoking, though it contains several flaws. . . .

Mr. Marsh treads on unstable ground when he asks:

If people really come to believe, as Sagan suggests they should, that they have been brought into existence through blind chance in a vast and pointless universe which originated with a mysterious explosion and will end in oblivion, is it likely that they will also feel that they owe some sort of mysterious “loyalties . . . to the species and the planet” and that they have an “obligation to survive . . . to that Cosmos, ancient and vast, from which we spring”? Talk of loyalties and obligations makes sense in religious terms; to Sagan’s world view the more likely response is a combination of nihilism and hedonism.

I do not agree. Need an individual believe in life after death and a hereafter to give his life meaning? Many people manage to live meaningful lives without these beliefs. The fact that the universe will destroy itself tens of billions of years hence need not stand in the way of human progress any more than the fact of a person’s inevitable death need stand in the way of his personal progress. There is so much the human species can accomplish between now and the time our star goes off “the main sequence” or the time that the universe explodes into another “big bang” or contracts into an enormous black hole. The pot of gold at the end of this rainbow may not be heaven or eternal life, but it will be the knowledge that we have realized our full potential as an intelligent species, something which we can never experience if we allow the millennia-old loyalties to clan, tribe, religion, nation, and race to cause four billion years of terrestrial evolution to go up in a cloud of subatomic particles. Loyalty to species and planet may not seem as romantic as Mr. Marsh thinks when the alternatives are considered. It may be the only road to survival.

Mr. Marsh’s statement that “thousands of years of history have shown that the widely held belief in an already received message from an even greater authority [than extraterrestrials] has not succeeded in making men love other men . . .” completely ignores the significance that a “close encounter,” whether in “person” or through the medium of a radiotelescope would have for humanity. Sagan never claims that a message or a visit from extraterrestrials would create automatic “peace on earth and good will toward men.” But it would, as he says, “deprovincialize biology,” and at least give us a true knowledge of our place in the cosmos, which is something that no religion anywhere has really been able to do. The scientific impact it would have would be unparalleled and unequaled by any other discovery in the history of science. And the knowledge we would gain from a civilization that has been around longer than we have, perhaps eons longer, could teach us how to solve the problems that have all too often been the causes of wars. At any rate, we would gain a sense of our uniqueness in a universe of exotic life forms, and with the passage of time, a commitment to preserving this uniqueness that, for the first time, would lead humanity into the realization of a mature civilization.

Ellen Leitner
New York City

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To the Editor:

Jeffrey Marsh’s penetrating comments on Carl Sagan’s Cosmos apply equally well to a significant number of today’s “orthodox” scientists. Mr. Marsh ought to have equal time on TV—or at least equal exposure—to show that there is more in science and society than is dreamed of in Sagan’s (and conventional science’s) cozy but uni-dimensional cosmos.

Jule Eisenbud
University of Colorado Medical School
Denver, Colorado

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Jeffrey Marsh writes:

Stanley L. Weinberg and D. A. Dominguez have accused me of error in stating that a fact must be directly observable. They also argue that I was wrong when I described evolution as a theory rather than a fact. Walter Rosenauer assails me for my failure to admit that science has shown that the world is ruled by chance, not by divine providence, and Ellen Leitner is offended by my skeptical response to Carl Sagan’s belief in salvation through extraterrestrial communication.

I must plead guilty to the charge of insufficient rigor in using the phrase “directly observable” in an attempt to spare readers a lengthy epistemological analysis of the complex (and controversial) relationship among such concepts as observation, fact, hypothesis, and theory. I hope that I can continue to avoid this exercise by agreeing in loose terms that a fact may be directly or indirectly observable, as long as there is not too great a gap between what actually is observed and the “fact” which is inferred. In the case of evolution, I continue to believe that there is too great a gap. A heroic effort of extrapolation is required to go from observations such as those on plants and bacteria cited by Mr. Weinberg to the theory summarized by Sagan and endorsed by my critics which postulates a process occurring over billions of years and relying on purely random occurrences to transform a hypothetical “soup” on the primeval earth into the full range of complex life forms and behaviors existing today. Mr. Weinberg himself distinguishes between what he terms the “fact” of evolution and the “theory” of evolution of which he cites several variants. In the absence of direct observation, a quantitative theory of how the process happened on the postulated time-scale, and a set of falsifiable predictions, critics more rigorously inclined than I am have argued that evolution should not even be afforded the status of a scientific theory, so I believe that my original statement, “the concept of evolution is accepted by the mainstream of biologists,” is both neutral and accurate.

Mr. Rosenauer seems undecided whether scientific activity and religious belief are non-intersecting (as he states at one point) or antagonistic (as he implies later). I would argue that in formal terms they are non-intersecting, but that underlying religious beliefs can have a profound motivating effect on scientific activity, as I believe they did in the particular cases of Kepler and Newton. I think that the viewer of Sagan’s program on Kepler, or the reader of his section on Newton, would come to the same conclusion. It is of course possible to argue, as Sagan does, that these religious beliefs were a regrettable reflection of the prevailing intellectual climate of the times in which Kepler and Newton lived.

Mr. Rosenauer’s one-sentence summary of my position is absolutely accurate. But his statement that the “scientific view [is] that chance factors account for the origin of the universe” I find impossible to understand logically. Leaving aside this technicality, the idea that the universe is ruled by chance is of course profoundly irreligious; it is also not a scientific statement. The existence of statistical laws, however, is no more an embarrassment to any theology which includes both divine omniscience and human free will than is strict causality.

If Miss Leitner really believes in Sagan’s randomly generated universe, I do not see how she can speak of the “potential” of any species, which surely implies some teleological purpose to evolution. I fail to see why an encounter with an alien intelligence would give us a sense of our uniqueness; by definition we are more unique if we are alone. Finally, Miss Leitner’s attempt to restate Sagan’s case for the transcendental importance of communication with extraterrestrials (and, of course, as I neglected to point out in my review, there is not one scintilla of evidence for life in the universe outside earth) merely echoes his failure. The only people whose fundamental behavior might be altered by the receipt of an interstellar radio communication are those who believe that the medium is the message, and they are not a promising audience.

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