Guest essay by Rick Wallace

A useful method for gaining an initial understanding of complex social-psychological phenomena is to collect and compare case studies. Despite the humble character of such material (with respect to its role as evidence), it still performs the vital service of grounding discourse in concrete fact, thereby giving it a substantiality that it would otherwise not have. Another benefit is that once a case study has been brought to peoples’ attention, they can make their own assessment after exploring it further for themselves.

In the course of a personal study of evolutionary biology, which includes the phenomenon of speciation, I had occasion to look over a number of papers concerned with the question of how to define what a species is. Although there are now numerous species definitions, the leading one still seems to be the “biological species concept” or BSC, associated with the names Dobzhansky and Mayr. Roughly speaking, under this definition a species is a reproductively isolated population; this implies that the gene flow from outside that population is at most highly restricted and possibly non-existent. This definition is associated with an account of speciation in which the most common scenario is for two populations that once formed a single species to become separated geographically so that they come to diverge. When they have diverged sufficiently, so that hybrids are infertile or inviable, then they can be regarded as separate species. This is called allopatric speciation.

Now, as I said, by a rough consensus, this is still probably the leading definition – at least for organisms that reproduce sexually. What is interesting is that for 30 to 50 years it has been subjected to continuous criticism from numerous people in the field, including botanists, paleontologists, systematists, as well as field zoologists. Along with their critiques, some have proposed alternative definitions, so that according to a fairly recent (1997) summary, more than 20 different definitions have been put forth. (From what I can tell, the penchant for coming up with alternative definitions has fallen off since the turn of the century, probably because the range of possibilities has now been pretty well covered, so this number is probably still accurate.)

Very early on, the practical usefulness of the BSC was questioned. Here is a typical comment:

“The biological species concept considers the species as a collection of genetically similar populations capable of interbreeding that, through genetically determined isolating mechanisms, are evolving in a pattern distinct from other similar collections of populations. This concept … is the most widely accepted definition of species, although its application to practical taxonomic work is limited and its conceptual bases flawed …”1

And here is another, even stronger, statement. After discussing various perceived deficiencies, especially having to do with ancestor-descendent relationships, the authors say:

“For these reasons, the Biological Species Concept … is an obstruction to empirical evolutionary biology.”2

To be sure, there are plenty of substantive problems, such as, (i) difficult to unravel species-complexes in animals (e.g. birds, butterflies) and even more so in plants, where there is sometimes evidence of widespread and continuing hybridization (and therefore possible gene flow) between closely related species, (ii) uniparental ‘species’, where the clonal lines together retain common, species-like features, just like biparental species (iii) the need to develop classifications that include both extinct species and living ones. One upshot is that many botanists and zoologists have concluded that the BSC cannot replace the classical taxonomic species, based on phenotypic (e.g. morphological, but also genetic) features. Others have argued that “evolutionary” or “phylogenetic” species concepts should be taken as primary. And some researchers have gone further and called for abandoning the notion of species altogether, a position at the opposite pole from the assertion of others that species (as opposed to higher taxa) are the focal points of evolution.

To give the reader a flavor of the discussion, here are some quotes from a 1992 review of a book devoted to the topic of species in biology (obviously, the author of the review is not a nonpartisan observer):

“Most authors … admit that species are real and not arbitrary groups demarcated by humans. There is, however, no agreement about the nature of species, save that it is not adequately described by the biological species concept. Once again we hear the standard catalogue of objections to Mayr’s definition … “To replace the biological species concept, the authors proffer nearly a dozen new species concepts, some of them quite ingenious. “The authors snipe at one another’s concepts, with some of the best criticisms coming not from biologists but from philosophers … When the dust has settled, however, only Mayr is still on his feet, with his original concept remaining the simplest and most useful …”3

In other words, to the degree that the BSC remains the prevailing species definition, it is more a matter of still standing after a vigorous and drawn-out brawl than because it has been upheld by workers in the field collectively as the one true account of things4. But I would contend that this is what real scientific consensus looks like. In such cases, discussants never take the ideas in question as sacrosanct, and because – at least in a normal, healthy science – intelligent inquiring intellects are constantly evaluating ideas for themselves and setting them against their own experience, such ideas are subject to vigorous and even harsh examination, often leading to a range of opinion, especially if there are serious conceptual or semantic difficulties (as there are in the case of the species concept).

(In my opinion, this is why Patterson et al. in their 2008 BAMS article were able to say, truly but perversely, that in their terms there was no “consensus” regarding future warming or cooling back in the 1960s and 1970s. At that time climatology was still a normal area of science, so there was bound to be disagreement, especially about future trends.)

Another example comes to mind in this connection, which I will discuss very briefly, since I don’t know the field at all. This is the status of quantum mechanics. Reading Lubos Motl’s blog, The Reference Frame, over the years, one notices that although this is clearly the leading ‘paradigm’ in subatomic physics, there are still any number of people who are quite willing to argue endlessly about whether it is truly valid. Now in this case, these may often be zealots on the fringe, but the message is the same: in a real field of science people don’t line up behind a so-called “consensus”. The image one has, even of a well-established doctrine like quantum mechanics (one which, I gather, has been subject to tests of excruciating rigor for almost 100 years), is not of a phalanx of people standing shoulder to shoulder, chanting in Monty-Pythonesq unison, “This is the Truth!” Instead, there is a general assent along the lines of, “Yeah, this seems to be the way it is” or a more assertive, “Yup, this is the way things are.” And the attitude toward heretics is not expressed as, “You must believe!” but (at least until they become insufferable), “Well, you either get it or you don’t.”

Thus, in real science any state of agreement is labile at best – and establishing a consensus is about the last thing on peoples’ minds. I would go so far as to say that under these conditions, as often as not, a leading idea is a target to take aim at rather than a flag to rally ‘round.

Obviously, this cast of mind is utterly different from what we find in the AGW arena. Which in itself is compelling evidence that the motivations are different in normal science and in (C)AGW.

This brings me to my final point.

What is perhaps most fascinating about modern spectacles like the AGW movement (and here I’m thinking in particular of the Moscow show trials of the 1930s) is that the truth is always right there in front of everyone – and it is always apparent to those who can see. For such people, and this is true of most (but probably not all) AGW skeptics, the fact that some sort of charade is in progress is obvious, even if one does not characterize it in those terms.

Once this is understood it also becomes clear why these affairs are always imbued with an air of intimidation. (In fact, perhaps more than anything else, this aspect is what gives the game away.) This is something that is never present in real scientific discourse, even on those occasions when things get nasty. In such cases (for example the controversy over the wave nature of light in the early 19th century), scientists may get catty, and they may even act to keep work out of print (by negative reviews). But there is no real intimidation (at least none that I know of, and I have some personal experience in this department); there is never a covert message to the effect that, “This is the proper account – and you had better not contradict it!”

1R. R. Sokal. (1973). “The species concept reconsidered”. Systematic Zoology, 22(4), 360-374.

2D. R. Frost & A. G. Kluge. (1994). “A consideration of epistemology in systematic biology, with special reference to species”. Cladistics, 10(3), 259-294.

3J. A. Coyne. (1992). “Much ado about species”. Nature, 357, 289-290.

4Just for the record, I will note that at this point it seems clear that no one of these concepts will prevail over the others, and in fact a more multi-faceted approach to the problem which takes into account several of the species-definition proposals seems to be emerging.

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