Responses to Some Common Objections to “The Short Proof of Evolution”
[This text, which has been created by Ian Johnston of Malaspina University-College, Nanaimo, BC (now Vancouver Island University), in in the public domain and may be used by anyone, in whole or in part, without permission and without charge, provided the source is acknowledged--released January 2005]
The following remarks have been prompted by e-mail objections over the past three years to the article “The Short Proof of Evolution.” They are intended to serve as a response to those who wish to challenge the validity of the case made there for evolution as a general concept explaining the development of animal and plant species, without reference to how that process might actually work. I will not repeat here the case made in that earlier essay. Those who wish to review it can consult the following link: Evolution). The paragraphs below list most of the common objections I have received, together with a brief response to each one.
My most general response to almost all objections is the following: Would the person making the objection please indicate where precisely the argument laid out in the essay is fallacious? Is there a particular factual claim there which is not warranted? Or are the facts correct but the reasoning erroneous? If the response does not directly answer one of those questions but instead raises extraneous issues, then it is not much use as a challenge to the case made in the essay.
This rubric includes all complaints which have no content. For example, “What you have said proves nothing,” “People have shown that Creationism is scientifically valid,” or more succinct pejorative comments (often about the personality of the author) or direct appeals to scripture or some unnamed authority. Such objections, however sincere, are, of course, empty, because they offer no reasonable ground for disagreement and merely indicate the writer’s displeasure with the conclusions.
ORIGIN OF LIFE OBJECTIONS
The most common objection to the case made for evolution is the question, “But what about the origin of life?” What about it, indeed? As the article itself makes clear, questions about the origin of life, though addressing a related issue, are red herrings, since evolution concerns itself with the diversity of species once life is established on earth, not with how life first began. So such a question is rather like raising doubts about how steel is made in any argument about how a car engine works. Naturally, the origin of life on earth is a fascinating issue, one which scientists continue to explore. They have come up with a number of hypothetical possibilities, but as yet there is no favourite theory, nothing which has yielded a wealth of predictions which one can easily test to confirm or reject the hypothesis.
Some correspondents seem to think there is a contradiction in claiming that living things must have a living parent and the fact that we don’t yet have a scientific theory which explains fully how life on earth began and that until that question can be answered, all scientific thinking about the development of species is invalid. But that is nonsense. We don’t know many things about the most basic cell operations of, say, many viruses and bacteria, and in most cases we don’t know (and certainly don’t need to know) the scientific origin of a particular agent of infection (its first appearance on earth), but we can still understand the way infectious organisms develop and change to affect people for the worse, and, on the basis of this knowledge, we can treat many diseases successfully. Would those who reject evolution on the basis of this faulty objection make the same claim about modern medicine and refuse to see a doctor when they need help to recover from an infection because there is an important “contradiction” in his understanding of the disease if he doesn’t know when and how it first appeared?
Moreover, those who argue that because there is no satisfactory scientific explanation at the moment, therefore there cannot be one and that thus some non-scientific (i.e., religious) account is necessary may well be, as so often in the history of science, jumping the gun. They might do well to heed the advice of Bishop Burnet all those years ago:
‘Tis a dangerous thing to engage the authority of scripture in disputes about the natural world, in opposition to reason; lest time, which brings all things to light, should discover that to be evidently false which he had made scripture to assert. . . . We are not to suppose that any truth concerning the natural world can be an enemy to religion; for truth cannot be an enemy to truth, God is not divided against himself.
Those who wish to focus on this point might also like to consider the following questions: Why does life have to have an origin? Could it not have always existed somewhere in this universe or a parallel one? Why does there have to be a “first cause” at all?
Any scientific explanation for the origin of life will, of course, have to involve matter and physical laws, without appeals to supernatural processes, and it will have to generate predictions which can be tested.
THE DEFENCE OF GENESIS AS A SCIENTIFIC DOCUMENT
Another common red herring is the claim that if we read Genesis allegorically, making each “day” a long period of time, then the sequence of creations described matches (more or less) the narrative developed by science. Hence, we ought to ascribe some scientific validity to the Biblical narrative.
Here again, the reasoning is fallacious. The fact that a confirmed scientific theory bears some resemblance to an old story provides no scientific justification for the story. The Greeks had old stories which explained the orbits and positions of many stars. These myths often involved transformations of human beings into celestial phenomena (as a reward or punishment). Science has developed and confirmed different theories for why these stars appear to move the way they do. Even if such ancient stories contain details also found, more or less, in scientific explanations, that confers no scientific value on those stories (useful as they may be for religious doctrine or literary delight).
OBJECTIONS TO DARWIN
A number of those taking issue with the case made for evolution point to some real or apparent difficulties with Darwin’s account of how evolution proceeds (that is, through natural selection). Again, as the original article points out, such objections are irrelevant. The general case in support of evolution derives none of its strength from Darwin’s work and would remain exactly as it is if we had never heard of Darwin or if we decisively refuted his theories. Such objections are easy to make, of course, because scientists themselves are always calling attention to certain problems with parts of Darwin’s theory, but they do not affect in the slightest the argument for evolution made in the essay. The theory of evolution was well known long before Darwin. His grandfather wrote a poem about it, and, some forty years before Darwin’s book first appeared, Lamarck published a comprehensive theory of evolutionary change. What’s significant about Darwin’s writing is not the general account of evolution but his description of how evolution proceeds.
To repeat the point: Darwin’s theory is an account of how evolution works. If there are problems with that theory or even if it is discredited, that does not disprove the existence of evolution. Just because we have problems agreeing how something works, that does not entitle us to claim that the phenomenon does not exist. If we’re not exactly sure how salmon find their way back to their spawning grounds, does that mean they don’t go there?
Hence, any appeal to problems with, say, the mutation rate or to the probabilities of random changes producing complex structures or to what is going on at the microscopic level, however pertinent they may be to a discussion of natural selection, are irrelevant to the argument presented for evolution.
THE “FOSSILS ARE MISLEADING” OBJECTION
One common objection takes issue with the claim that the rock layers of the earth (and the fossils they contain) indicate a sequence of geological events over a long period of time. Now, this objection has one great merit most of the others lack: it does engage the argument made in the essay by directly challenging one of the three factual claims upon which the argument rests. That, however, is its only merit. For those making this objection are explicitly or implicitly claiming that the geological record was made in a matter of days or weeks by a process as yet unexplained, other than by appeals to miraculous processes. But if we permit imaginatively created miracles designed to answer what we would like to believe to serve as reasonable explanations, then there is an infinite number of possibilities, all equally likely and all equally incapable of verification (for example, the once popular idea that the fossils were planted in the rocks by the devil to mislead human beings). Scientific enquiry achieved its favoured status largely because it delivered us from such irresolvable, sterile, and often bloody disputes.
The fossil record, especially the succession of different fossils in different rock layers (including many extinct species), is the most compelling evidence against the view that the earth was created quickly and has always contained the same forms of life and also the reason virtually all serious scientists eventually conceded (often with great reluctance) that the earth has a long history, a narrative that includes the appearance and disappearance of many different species.
It is also significant that no human remains occur in the fossil record except in the most superficial layers of the earth (graveyards, battlefields, flood plains, and so on). A more or less literal reading of Genesis, of course, would require that human remains occur alongside the remnants of all other created beings.
THE “EVOLUTION IS CIRCULAR” ARGUMENT
Allied to the objection listed immediately above is the claim that the argument for evolution is invalid because it is circular; that is, by stating that the fossil-bearing rocks indicate strata laid down over long periods of time at different ages of earth’s history, the arguer has assumed the truth that was in question. Hence, the structure of the argument is fallacious.
This objection is, of course, spurious. Science can plausibly explain and confirm that some rock formations are made by solid material and organic remains settling in water, that over time different rock layers will lie on top of each other, that, if the layers are undisturbed, the younger rock layers will lie on top of the older rock layers, and thus, that the fossil material in the higher undisturbed layers will be younger than the fossil material in the lower undisturbed layers. This claim is not something the argument simply assumes: it is based on hundreds of years of observation and testing. For a long time, oddly enough, it was used to defend the Genesis account of the Deluge, until people started to realize just how long it would take for physical processes to create what we see all around us and also how many floods there must have been.
THE OBJECTION BASED ON THE ABSENCE OF VISUAL CONFIRMATION
Others reject the notion of evolution outright (without reference to the argument) with the simple claim that it cannot be true because no one has ever seen a complete transformation of one distinct species into another (e.g., fish to reptiles). There may have been all sorts of minor developments of one species into another distinct but closely related species (an established scientific finding), but without such visual experience of a major transformation, so they say, evolution is just a “theory.”
Well, of course evolution is a theory, just as atomic structures, black holes, electricity, relativity, DNA, magnetism, and so on are “just theories.” But so what? We do not have direct visual evidence of these things with our own eyes (who has ever seen an electron or a molecule or a gene with the naked eye?). What we do observe, often with the aid of very sophisticated machines, are larger events which we explain as effects of those theoretical components. Most scientific theories involve natural elements that we cannot see. Those who seriously believe that this objection carries any weight need to become more familiar with the nature of scientific enquiry and the meaning of a scientific “proof.”
Science does not proceed by demonstrating that certain theories are irrefutably true. It demonstrates by repeated testing that they are not false. The more a theory is confirmed, the stronger the probability that the explanation it offers is correct. This process produces what amounts to the explanation which best fits the facts we have collected (even if the fit is not always complete). And how does such confirmation proceed? There are two main tests. The first is to make a series of predictions based on the theory and then to explore the validity of those predictions. If a prediction holds, the theory has been confirmed; if not, then the theory has been challenged, perhaps even disproved. The second method of confirmation is to see how the theory accounts for new, unexpected discoveries. Can these be explained in terms of the theory? If so, then the theory has been confirmed; if not, then the theory has been challenged or disproved. By these two tests, the theory of evolution is spectacularly successful: it has been confirmed countless times over the past three centuries (at least). It would take only one discovery to discredit the entire theory (e.g., the existence of a mammal fossil in the lowest rock layers). That has never occurred.
This aspect of scientific explanation gives the method its unique power. Unlike some other knowledge claims (like many of those based on scripture), discrediting or disproving a scientific theory does no harm to scientific enquiry itself. Quite the contrary. It forces scientists to come up with a more refined or a different theory which can better account for the anomaly, and hence it strengthens the explanatory power of science and of particular scientific theories, like evolution.
A number of objectors make a case that goes something like this: Here’s a problem that evolution has not yet explained in detail to my satisfaction (e.g., origin of life, evolution of a particular animal species or organ). Therefore, the whole theory is clearly wrong or invalid or “merely” a hypothesis. But no rational mind rejects an entire theory just because it is not complete. Physics is just as incomplete as biology (in the sense that there are many basic problems left to explain), yet no one objecting to evolution on these grounds makes similar complaints about Newton’s Laws. In fact, every time people drive their cars or ride in a plane they are demonstrating their absolute faith in those laws. To object that because a scientific theory cannot explain everything, it therefore explains nothing makes as much sense as claiming that because someone does not know every word in the English language, nothing he says in English is worth attending to.
What seems clear in such cases is that the thinking process which produces such objections has nothing to do with a reasonable analysis of a scientific argument; it stems from an absolute refusal to accept that argument’s conclusions and from a search (often rather desperate) for anything that looks like an apparent justification for such a refusal. One is perfectly free to reject the conclusion of a scientific argument, of course--after all, it is a free country--but to pretend that the incompleteness of some of the explanations offered by the theory is an adequate scientific reason for doing so is erroneous.
Finally, to argue, as some readers do, that just because we haven’t found complex vertebrate fossils (including human beings) in the lower strata doesn’t mean they are not there and that thus we should not consider evolution valid indicates a complete failure to understand the nature of scientific reasoning. Should we throw out the theory of gravity just because, for all we know, some day a stone dropped out of a window might fly upward?
THE OBJECTION THAT EVOLUTION FAILS TO MEET THE BASIC REQUIREMENT OF SCIENTIFIC THEORIES
Another objection questions the scientific validity of evolution by asking how it could ever be disproved (an essential requirement of any scientific theory). Since the theory does not demand that species become increasingly complex over time, the discovery of a complex fossil in the older rocks, some people claim, would not necessarily “disprove” the theory. That would simply be a serious anomaly which the theory could then presumably justify. So, according to this objection, no evidence could ever be found to refute evolution. Hence, the theory of evolution is, just like Freudian or Marxist theory, infinitely adjustable to fit any evidence whatsoever and thus has no scientific value.
This objection, though more interesting than many others, is also fallacious. The theory of evolution predicts that the evidence, though incomplete, enables us (or will enable us) to construct a reasonable genealogy showing how over time some species change into new species or, conversely, how many later species have emerged from a series of changes in other earlier species.
The discovery of, say, complex vertebrate fossils in the oldest fossil-bearing rocks would be much more than a serious anomaly which the theory could account for with an adjustment or two. It would immediately raise the question, “From what earlier species did these forms arise?” The theory of evolution holds that we should be able to find or to predict an acceptable answer to this question. But it would be extraordinarily difficult, if not impossible, to provide a scientifically reasonable answer in this case, because there is no plausible scientific hypothesis which could account for the sudden emergence of a complex vertebrate form either from non-living material or from very simple single-celled organisms. That being the case, one would have to conclude that, however the complex vertebrate forms appeared, it is highly improbable that they were the product of evolution. Hence, the entire theory would be discredited.
Of course, one could come up with a hypothesis to account for the existence of such complex fossils among the earliest deposits, but such a hypothesis would either lie outside the realm of scientific explanation (e.g., the gods put the fossil there) or would require an extremely improbable claim (e.g., that there is some unknown mechanical process that can change a single-celled organism into a complex vertebrate in one step, or that a living vertebrate arrived on a comet from some other world, and so on). The latter claims have an explanatory value, but are so improbable that science would treat them with the utmost suspicion, if not reject them outright (rather like the claim, to borrow an example from Phil Dawe, that the sky is blue because the earth sits inside an emu’s egg–a statement which answers any questions about why the sky is the colour it is but does so with a hypothesis that is so improbable it has no scientific validity). The general point invoked here is that a scientific hypothesis, in addition to having explanatory value and being testable by the normal rules of science, must also be plausible.
WHAT ABOUT INTELLIGENT DESIGN?
The Intelligent Design argument, which holds that the development of organic life must be guided by some higher-order intelligence responsible for the incredibly complex designs of particular structures (e.g., the human eye), is entirely compatible with the theory of evolution (although not with Darwin’s account of how evolution works). All one has to concede is that the process governing evolution is supernatural rather than natural. This is not a scientific position, of course, since any invocation of non-natural causation in explanations about nature lies outsides the methods of science. But it is one way to believe in evolution without abandoning a faith in god or gods.
Given the relatively simple claims of the Intelligent Design argument, it obviously provides no direct encouragement for any particular system of belief or set of creation stories. All it states is that there must some higher entity or entities guiding the process.
The argument against Intelligent Design has nothing to do with the theory of evolution. It stems from the logical problem (pointed out long ago by Spinoza and Kant) that one can make no reliable inferences about supernatural entities on the basis of natural observations. The wonderful complexity and symmetry in nature may well encourage faith in a supernatural designer, but those qualities do not enable one to make firm conclusions about the existence of such a divine presence or about any attributes such a presence might or might not possess.
Those who wish to put Intelligent Design into a school curriculum are clearly wrong when they want it to be part of a science or a philosophy curriculum, since the concept is basically irrelevant or of minimal interest to either subject area. Where it belongs is in any curriculum devoted to the History of Science, for the idea has played an extremely important role in the historical development of modern science. There are, no doubt, many advantages to teaching science historically, but such courses are usually in short supply, especially in secondary schools.
SCIENTISTS CLAIM TO BE OPEN MINDED BUT WON’T GIVE CREATIONISM OR INTELLIGENT DESIGN A HEARING
Why, many people claim, are scientists not more receptive to creationism. They state that their method invites rival theories, but shut the door on any meaningful discussion. Well, scientists are, in general, very open minded and ready to listen and argue about various theories (although often slow to get involved). But there are two caveats. First, the theory being proposed must be a scientific theory (i.e., capable of producing predictions which can be tested, without any appeals to supernatural causation, and so on). If it is not, then scientists will say that such a claim lies outside of their jurisdiction (i.e., science has no way of assessing the validity or usefulness of the theory). The theory might well be true (whatever that means exactly), but it is not science. This was part of the judge’s ruling in the recent (2005) Dover School case which decided that Intelligent Design had no place in the science curriculum (a decision endorsed by the Vatican).
The second caveat is that theory being proposed should not be one which scientists have already discredited, even though the theory might well meet the criteria of a scientific argument. Few scientists, I suspect, would be very interested nowadays in debating whether the sun or the earth is the focal point for our solar system or whether phlogiston is involved in combustion.
Of course, sometimes old theories, once discarded, can make something of a comeback. For example, the inheritance of acquired characteristics, a key element in Lamarck’s theory of evolution (and a view shared by Charles Darwin), was rejected in the 19th century after various experiments. However, in recent decades it has appeared again in studies of how environmental factors can affect mutation rates.
When critics complain that scientists are too dogmatic about evolution, they rather miss the point. Within the scientific community there is virtually no argument about evolution as the key metaphor in the development of life of earth, because there is no other scientific theory with the same explanatory power available. The same holds true for theories about our solar system. But I have yet to hear such critics complaining about the fact that Newton’s cosmology is too dogmatic and that we need to make room for theories about Elijah’s making the sun stand still. The persuasiveness of science arises, after all, because, unlike other systems of understanding the world, it does resolve some issues once and for all.
WHY WON’T THE SCHOOLS GIVE EQUAL TIME TO CREATIONIST ACCOUNTS OUTSIDE THE SCIENCE CLASS?
Obviously, as the courts have consistently recognized in the US, Creationist accounts of the origin of species or Biblical challenges to scientific evolution do not belong in the science class. The fact that they are not allowed in the publicly funded school elsewhere in the curriculum (except perhaps in some classes of comparative religion, where a number of accounts are studied) has nothing to do with science. The prohibition is the result of a political decision in a great many countries. And that decision, which is long established in many jurisdictions, was made generations ago by elected assemblies consisting, for the most part, of white Anglo-Saxon Christian men, the majority of whom (I suspect) were regular church goers.
They made the decision because they recognized that religious instruction in the schools is very divisive and an almost sure-fire way to generate significant social disruption both inside the school and outside it. History teaches us clearly that encouraging religious differences in schools leads to often mortal conflict in the wider society.
Those who find the decision unacceptable should thus direct their energies, not at the scientists or science teachers, but at the legislators. Before they do that, however, they might well refresh their memories with some of the historical facts of religious conflict in the West (starting perhaps with Northern Ireland).
ONE FINAL COMMENT
Those who wish to claim some sort of scientific credibility for Creationism (or Creationist Science) are, ironically enough, often undermining their own faith. Since science is the search for natural laws (preferably mathematically precise universal laws) which govern natural phenomena and since science requires rational procedures, a claim that Creationism has some scientific validity is imposing restraints on God, saying, if effect, that He must operate in accordance with what science has discovered or by the rules of scientific reasoning and not according to His will. If one denies this claim and insists that there are no restraints on God, who may observe or depart from reason for His own inscrutable purposes, then it’s clear that there is no scientific basis for that approach to the natural world. The bravest Christian spirits are those who boldly grasp this point and cry, with Tertullian, “Credo quia absurdum est!”
POSTSCRIPT FOR THOSE WHO STILL CLING TO THEIR OBJECTIONS
Suppose two good friends come to you to resolve an argument. Friend A is a fanatic about soccer, Friend B about basketball, and they have been having a long, fierce argument about which game is the one true game and which one should become the official sport of the community. Friend A argues that soccer must be the one true game because in soccer no one other than the goalie is allowed to pick up the ball during play (except to throw it in if it goes out of bounds) and because one has to propel the ball with one’s head or feet. Friend B argues that basketball must be the one true game because in it players have to propel the ball with their hands and are not allowed to kick or head the ball. Both appeal repeatedly to the rule books in their hands to insist upon the rightness of their cases and to point out the imperfections in their opponent’s argument.
What would you tell them? Well, if you’re still objecting to the argument for evolution, I have no idea what you would say. But in the spirit of reason I would tell them that their argument is stupid. The better game is a matter of choice, and appealing to the rule book of one game to discredit another game is irrelevant. Moreover, there is no super rule book in the sky which adjudicates between these games. So they can play soccer or basketball and abide by the rules of the game they choose, or they can play both if they’re prepared to switch from one rule book to another. But to demand that one game is inherently “right” or “better” and the other one “false” or “worse” in any absolute sense is, as I say, silly. And it’s equally silly (and probably more dangerous) to show up on the soccer pitch demanding the right to play by the rules of basketball, or vice versa.
In what way is this example any different from the interminable arguments between evolutionists and creationists (arguments which, incidentally, are not particularly interesting or challenging philosophically, scientifically, or theologically)?
[For a more detailed discussion of some of the points raised here, readers might like to consult the following essay: “Creationism in the Science Curriculum?”]