Tuatara: Volume 27, Issue 2, December 1984
Was Darwin Congenitally Incapable of Valid Thought?
Was Darwin Congenitally Incapable of Valid Thought?*
Croizat had a low opinion of Charles Darwin's ability as an original thinker. In this paper it is argued that it was Croizat's view of science and its methodology which led him to this conclusion. Croizat's criticisms of Darwin are analysed as a context in which to discuss and illustrate Croizat's view of what constitutes a ‘theory’ and an ‘explanation’. Also, when involved in theory rejection or selection Croizat is identified as a strict inductivist, though he claimed to be neither an inductivist nor a deductivist in the proper senses.
Leon Croizat was not unusual in regarding organic evolution as a continuous process. However, when most biologists analyse evolutionary events they tend to stress only the changes in body form that occur. Croizat, on the other hand, believed that evolution as a process could only be adequately analysed if, in addition to the consideration of change in form, one took account of the geographical space where those changes occurred and the time of their occurrence. In this way the evolutionary changes described are treated in an explicitly dynamic manner, and at least some of the details of the processes involved are also presented.
Croizat used the term ‘Panbiogeography’ to described his method of investigating evolution in terms of its three components—Space, Time and Form. Panbiogeography basically involves the analysis of living and fossil records of the geographic distribution of different taxa to enable the changes of location through time made by different forms to be mapped. This is not to say that the taxa always moved themselves around over the surface of the Earth, for the surface of the planet changes as well as the living beings on it. As Croizat would put it: Earth and Life evolve together.
Croizat considered this aspect of biogeographical studies to be self apparent and was highly critical of other schools of biogeographic thought, particularly the biogeographic theories developed in the context of Darwin's theory of evolution. Indeed, Croizat appears to believe that Darwin was greatly at fault for not developing the ideas of panbiogeography himself.
Croizat (1964, 1981) even attempted to explain why he thought Darwin failed to discover panbiogeography. He (1964:637) wrote that:
“He ((Darwin)) † could not do it because he was not born to it. He had a science of dispersal ready-made in his hand in 1845, but when he began to think of it in term ((sic)) of general ideas he cracked up on the spot.”
Whilst he accepted that Darwin was a ‘very able observer’, Croizat (1964:637) concluded that
“He ((Darwin)) was on the other hand congenially not a thinker.”
This paper has two aims. The first is to show that Croizat's low opinion of Darwin's ability as a thinker is wrong. This in itself is unimportant but the attainment of the first aim will be used as a vehicle to introduce and discuss particular aspects of Croizat's work, which is the second aim.page 128
The aggressive style Croizat habitually used can sometimes be blamed for obscuring the otherwise clear argument he presents. In particular, the rhetoric Croizat used when he critised Darwin for not discovering panbiogeography can be considered to be propaganda, designed to shock people out of what Croizat clearly believed to be unfounded hero worship. Sadly, in this case, the apparent wish to discredit Darwin, combined with Croizat's particular view of science, appears to have led him to make claims about Darwin for which there is no solid foundation.
An analysis of the arguments and statements behind Croizat's conclusion (cited above) will show that he had an unorthodox understanding of what is referred to by the terms ‘theory’ and ‘explanation’. This, on top of his inductivist view of science, made Croizat blind to alternative interpretations of Darwin's writings.
In the analysis much use will be made of direct quotation. Hopefully, this will, at the same time, illustrate both Croizat's style and wit, as well as convince the reader that Croizat's views are not being misrepresented.
Darwin's Proximity to the Discovery of Panbiogeography
Croizat repeated on numerous occasions his claim that Darwin had been very close to discovering panbiogeography. He (1981:505-506) stated that:
“Although Darwin proved incapable of formulating a viable theory of dispersal in the quoted text ((Origin of Species, 6th edition)), he nevertheless was not far from achieving that viable theory that he so grandly muffed when opening the door to the concepts of centre of origin, migration, and its means.”
He went on:
“The difficulty in understanding an intricate process and the mind's natural repugnance for paradox, readily account for the fact that an author who, like Darwin, has the correct solution of a major problem almost within his grasp, may eventually flounder into the inconsequential and erroneous instead of driving straight over the last few yards that still separate him from his goal.” (Croizat, 1981:509).
Clearly, Croizat thought that if Darwin had been a thinker of any standing he should have been capable of producing the theories that were, in fact, left to Croizat to invent. That Darwin failed, given the information available to him, Croizat found incredible and is one of the reasons behind his low opinion of Darwin's intellect. He wrote (Croizat, 1981:509):
“Darwin was one of the first naturalists to discover and report vicariance, nearly a century-and-a-half ago. But this epochal discovery fizzled out in his hands in a remarkable, even incredible way.”
Having established that Croizat thought that Darwin was actually incapable of producing a theory of panbiogeography we can now attempt to answer the question of why Croizat should have had such an opinion. This will require a consideration of what Croizat took to be a valid explanation and how this differed from his view of what constituted a theory. Such a consideration is necessary because it will allow us to appreciate how Darwin was able, quite validly, to reach conclusions quite different from those that Croizat believed to be obvious. It is plain that Croizat did not appreciate that his scientific methodology affected his view of Darwin's work. It will be shown that Croizat was wrong when he stated that:
“It is incredible that Darwin, master of factual observations of paramount biological significance, proved unable to reach obvious conclusions;.… It is page 129 no doubt true that at times even the keenest minds muff what in restrospect seems unmuffable, but this excuse can hardly apply in Darwin's case.” (Croizat, 1981:514, my emphasis).
Croizat's Scientific Methodology
Croizat was an inductivist. This claim is supported by the fact that he praised and supported a statement by S. A. Cain which included the following (Croizat, 1964:595):
“What is most needed in these fields ((zoogeography and phytogeography)) is a complete return to inductive reasoning with assumptions reduced to a minimum and hypotheses based upon demonstrable facts and proposed only when necessary.”
Unfortunately, the problem of determining whether Croizat was an inductivist or not is aggravated by Croizat's unusual usage of the term ‘deductive’. He wrote about Cain's usage of the term:
“…deductive for Cain basically refers to arguments rigged up to bolster aprioristic, theoretical assumptions. I have used the same adjective—unconventionally—in connection with reasoning which deduces ((induces)) the necessary conclusions from carefully observed facts of nature.” (Croizat, 1964:595).
In another discussion of his usuage of the terms ‘inductive’ and ‘deductive’ Croizat wrote (1978:210):
“I have already acknowledged that I applied the adjective ‘deductive’ in a sense contrary to convention (Croizat, 1964:595). Hence my use of the word may be equivalent to the ‘inductive’ of the learned world—an inversion for which I stand guilty.”
But he continued by demonstrating that he recognized the differences between induction and deduction and even claimed to have used both principles in the development of his ideas.
However, after making this claim he stated that (1978:211):
“I think that drawing a sharp line between what really is, or only seems to be inductive and deductive, except in rigid logic, is difficult.”
From all of this it might appear that Croizat was eclectic in his approach to making inferences about natural phenomena; that he was neither an inductivist nor a deductivist.
However this may be, Croizat's view of what was implied when a theory was refuted demonstrates that he believed theories and explanations to be produced inductively. In a revealing passage Croizat discussed the significance of testing a theory against new data. He was disagreeing with S. J. Gould who wrote that (Croizat, 1981:502):
“We are always ready to watch a theory fall under the impact of new data, but we do not expect a great and influential theory to collapse from a logical error in its formulation.”
Croizat (1981:502) replied to this by stating:
“In contrast to Gould, I would be inclined to believe that a theory falls under the impact of new data precisely because it is vitiated by some (one or more) logical errors in its formation. In my thought, a theory anticipates what the facts, when fully known, will demonstrate to be correct. Its failure when the facts tell otherwise, points to a logical error in its formulation.”
This claim, by Croizat, means that all falsified theories must have collapsed due to logical errors in their construction. For this to be the case each general theory must have been induced from a limited set of facts. If such a theory is then shown to be false the logical induction which produced it must have been in error. Hence, if the theory is falsified it must page 130 have contained a logical error. Anyone agreeing with this scheme must be an inductivist, thus the claim that Croizat was an inductivist can be made safely.
As well as being an inductivist Croizat also had a rather unusual understanding of the properties of explanations and theories. That this was so is best illustrated by a discussion Croizat made about Darwin's theory of coral-atoll formation. Croizat (1964:603) wrote about this theory:
“This explanation is often miscalled a theory which does not strike me as justified at all. The term theory has been of course used in so many different meanings that it can hardly be but shop-worn, but I should think that it can in no place apply to a rigorous demonstration by which something is finally explained that once was obscure and unknown. As the reader is soon to see, Darwin indeed explained atoll-making, which of course means that he did not only theorize on its account.”
It is difficult to understand how a theory can fail to be explanatory, even with an inductivist view of science. But Croizat appears to believe that theories are always speculative, untried entities which are of doubtful use owing to their not being based upon (induced from) carefully observed facts of nature. ‘Explanations’, however, because they are so based (in Croizat's opinion), may be treated with respect. If this is the distinction that Croizat makes then his choice of example is very unfortunate. Darwin wrote concerning his theory of atoll formation (Barlow, 1958:98):
“No other work of mine was begun in so deductive a spirit as this; for the whole theory was thought out on the west coast of S. America, before I had seen a true coral reef. I had therefore only to verify and extend my views by a careful examination of living reefs.”
There is, in fact, no logical distinction between scientific theories and hypotheses. They can both be modelled crudely by the simple statement: If G and C then P; where G is one or more general laws, C are the initial conditions relating to a particular instance, and P is the prediction deduced from G and C. If P should turn out to be the case then the statements in G, given C, are said to explain P. Thus, all theories and hypotheses must be explanatory if they are to be scientific (testable). This, of course, does not mean that they must also all be true for it is commonly the case that some aspect of an explanatory hypothesis turns out to be false; but, happily, the responses to such discoveries often lead to the growth of science. It must be remarked, for completeness, that it is also true that not all explanations are hypotheses.
However the case may be with Croizat, he certainly treated what he termed ‘explanations’ with respect whilst ‘theories’ were definitely frowned upon. An example of this can be seen in Croizat's continued discussion of Darwin's coral-atoll theory. Croizat was uncharacteristically complimentary about Darwin when describing this theory. The reason for this unusual praise is soon found. In Croizat's (1964:604) own words:
“Darwin's explanation—not theory of course; this explanation holds good today and so it will into the future, in principle when not in every detail—amounts to the affirmation of one of the cardinal axioms of (pan)biogeography which I have worded as follows: Earth and life evolve together.”
Croizat praised Darwin for this particular theory because it implied a principle very close to Croizat's heart.
Croizat's Erroneous View of Darwin's Work
We are now in a position to appreciate Croizat's anaylsis of Darwin's biogeographic theories. Croizat gives a detailed discussion of the treatment page 131 Darwin gave to the dispersal of the biota that the latter found upon the Galapagos Islands. We will be able to see in this discussion how Croizat's view of science prevented him from appreciating what Darwin was actually doing in his analysis.
Croizat reprinted the following passage from the 2nd edition of The Voyage of the Beagle (Croizat, 1981:513-514):
“It is the circumstance that several of the islands possess their own species of the tortoise, mocking thrush, finches, and numerous plants, these species having the same general habits, occupying analogous situations, and obviously filling the same place in the natural economy of this archipelago, that strikes me with wonder… The only light which I can throw on this remarkable difference in the inhabitants of the different islands is, that very strong currents of the sea, running in a westerly and W.N.W. direction, must separate, as far as transportal by sea is concerned, the southern islands from the northern ones; and between these northern islands a strong N.W. current was observed, which must effectively separate James and Albemarle Islands. As the archipelago is free to a most remarkable degree from gales of wind, neither the birds, insects, nor lighter seeds would be blown from island to island. And lastly, the profound depth of the ocean between the islands, and their apparently recent (in a geological sense) volcanic origin, render it highly unlikely that they were ever united; and this, probably, is a far more important consideration than any other, with respect to the geographical distribution of their inhabitants.”
Croizat (1981:514) had the following to say about this passage:
“He ((Darwin)) perceived the importance of vicariance as a fundamental law of nature; he saw that “species” and “subspecies” (understood in the usual taxonomic sense) could not be discriminated absolutely, inasmuch as their limits are subject to the play of individual opinion; and he adopted ther happy term “representative” as applied to species and subspecies. He was assured that casual means of dispersal among the islands were of little importance; he was satisfied that the plants and animals of the islands were basically American in their relationships. Thus, he had the whole of evolution and panbiogeography snugly in his hands in 1836. All that remained for him to do was to reason, from his own observations in the light of the axiom that earth and life evolve together, that it could not be true that the ocean unbounded lay forever there, where the Galapagos now stand; that the islands could not have originated burning and lifeless, from the depths of the eastern Pacific, but do on the contrary represent the fragments, altered by late vulcanism, of an earlier history, of a former extension of the American mainland.”
From this it is clear exactly what it was that Croizat wanted Darwin to produce from the evidence before him. To Darwin, however, it would have been far from obvious that the islands could not have originated ‘burning and lifeless’ from the sea. To him a volcanic oceanic origin for the islands was strongly supported by a number of different sources of evidence which he could not ignore. We can see from a number of passages that Croizat quotes from Darwin's The Voyage of the Beagle that Croizat was aware of this diversity of evidence (Croizat, 1964:610-611):
“Seeing every height crowned with its crater, and the boundary of most of the lava-streams still distinct, we are led to believe that within a period, geologically recent, the unbroken ocean was here spread out… Why on these small points of land, which within a late geological period must have been covered by the ocean, which are formed of basaltic lava, and therefore differ in geological character from the American continent,.… And lastly, the profound depth of the ocean between the islands and their apparently recent (in a geological sense) volcanic origin, render it highly unlikely that they were ever united;”page 132
Croizat dismissed Darwin's claim that the Galapagos were never united with the mainland despite Darwin's appeal to a wide array of geological evidence. Commenting on Darwin's account of the biogeographic position of the Galapagos, which included the passages from Darwin just quoted, Croizat (1964:611) stated that:
“It is right that he ((Darwin)) had the facts well in hand before he ever began to think of “Transmutation of Species”. It is true that he assumed for these islands an “oceanic origin”, but it is also true that he was aware of much that would, quite factually, not give easy comfort to this understanding.”
By claiming that Darwin had only ‘assumed’ an ‘oceanic origin’ for the Galapagos, Croizat is effectively ignoring and denying the stratigraphic evidence which Darwin produced and had to account for. That Croizat failed to see that Darwin had not just assumed a recent volcanic origin for the islands, but had rather tested this claim against field evidence, is due to the strange distinction Croizat made between theories and explanations. Croizat appears to believe that Darwin had only theorized (equals speculated) about, and had not provided an ‘explanation’ of, the present day distribution of the Galapagos biota. Of course, there can be only one true explanation (although it may never be found) and Croizat presumably believed that this could be discovered using induciton. It would appear that because Darwin did not produce the same explanation/theory as Croizat, the latter dismissed Darwin's efforts as incompetent. In fact, Croizat's explanation of the dispersal of the Galapagos biota is only an alternative explanation to that proposed by Darwin. What is required, instead of rhetorical attacks on either Croizat or Darwin, is some way of distinguishing which of the theories should be accepted and which rejected; it would appear that in the case of the Galapagos a geological test is required.
Are There Differences Between Croizat's Theory and Darwin's?
Darwin was aware that more than one explanation for the same phenomenon was possible. A result of this is that he put forward a number of possible solutions to the problem of explaining distribution patterns. They all, however, have a common assumption and that is that the same species cannot have been produced independently in two or more different places. The idea that Darwin was opposing when he wrote his On the Origin of Species was the so-called theory of Special Creation. This piece of information is required if one is to understand some of Darwin's statements. Unfortunately, Croizat appears to forget about Darwin's opposition to Special Creation; he quotes Darwin's Origin (Croizat, 1981:503):
“We are thus brought to the question which has been largely discussed by naturalists, namely, whether species have been created at one or more points on the Earth's surface. Undoubtedly there are many cases of extreme difficulty in understanding how the same species could possibly have migrated from some one point to the several distant and isolated points, where now found. Nevertheless the simplicity of the view that each species was first produced within a single region captivates the mind. He who rejects it, rejects the vera causa of ordinary generation with subsequent migration, and calls in the agency of a miracle.”
Croizat takes this to be Darwin's claim that the same species cannot evolve independently in more than one region.page 133
As long as Croizat did not accept that the same species could evolve independently in different places the differences between his view and Darwin's reduces to the simple one of how vicariant distributions arise. Darwin does not deny that ‘means of dispersal’ can operate to enable species to cross barriers to free range extension, whilst Croizat believes that they do so only rarely. On the other hand, Darwin did not restrict himself to such explanations. Croizat (1964:631) quotes Darwin as saying, in the 6th edition of the Origin of Species:
“It seems to me ((Darwin)), as it has to many other naturalists, that the view of each species having been produced in one area alone, and having subsequently migrated from that area as far as its powers of migration and subsistence under past and present conditions permitted, is the most probable. Undoubtedly many cases occur, in which we cannot explain how the same species could have passed from one point to the other. But the geographical and climatal changes which have certainly occurred within recent geological times, must have rendered discontinuous the formally continuous range of many species. ((This describes a mechanism which Croizat would surely endorse.)) … Whenever it is fully admitted, as it will someday be, that each species has proceeded from a single birthplace, and when in the course of time we know something definite about the means of distribution, we shall be enabled to speculate with security on the former extension of the land.”
Following this, Darwin could not deny that it was possible for a species to obtain a vicariant distribution without one of the populations involved migrating away from the other.
Croizat was wrong to reject Darwin's explanation of the dispersal of the Galapagos biota, for it was a valid explanation which has received some corroboration from the field evidence. A corollary of this is that Croizat was also incorrect in his claim that Darwin was incapable of thinking (reasoning validly). In the context of the level of scientific development of his day (particularly geology) Darwin would have had grave problems had he produced only a geological or geographical explanation of the production of vicariant distributions.
Croizat was mistaken in his criticism of Darwin because his views of science made it impossible for him to understand what Darwin was doing. The differences between the Darwinian and Croizat's approach to explaining dispersal need to be clearly and explicitly stated; for example, it is unclear whether or not Croizat accepted the assumption that the same species cannot evolve independently in two or more regions. Only after the identification of differences can tests be made to see which account provides the most accurate representation of the development of the world's biota.
I would like to thank both Grant Gillespie and Michael Heads for critically reading this manuscript. The latter disagrees with most of the content of this paper so I am especially grateful to him for his efforts.
Barlow, N. 1958. The Autobiography of Charles Darwin. Collins, London.
Croizat, L. 1964. Space, Time, Form: The Biological Synthesis. Published by the author. Caracas (Venezuela, S. A.)
Croizat, L. 1978. Deduction, Induction and Biogeography. Syst. Zool. 27:209-213.
Croizat, L. 1981. Biogeography: Past, present and future. Pages 501-523 in Vicariance Biogeogrphy: A Critique. Editors: Nelson, G. and D. E. Rosen. Columbia University Press, New York.
* Present Address: Department of Zoology, Victoria University of Wellington, Private Bag, Wellington, New Zealand.
† In this article (()) indicates a notation by the present author.