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Topics to which these philosophical and scientific ideas are addressed include the nature of the organism, the limits of neo-Darwinian evolutionary theory, the significance of genomics, the biological status of human races, and the evolutionary and developmental plasticity of human nature. Keywords: philosophy of biology , genomics , epigenetics , microbiology , developmental systems theory , evolution , organism , human nature. Forgot password?
- David L. Hull.
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Don't have an account? All Rights Reserved. OSO version 0. University Press Scholarship Online. Sign in. Not registered? Sign up. Publications Pages Publications Pages. Search my Subject Specializations: Select Users without a subscription are not able to see the full content. First and foremost are the empirical constraints. A significant part of what makes one revised version of a theory last and come to dominate is its superior ability to resolve empirical anomalies, to suggest novel tests - ideally, tests that force choices among competitors - to account for evidence formerly not thought of as evidence for that theory at all, and so on.
I would argue that, while this is not the only environmental factor shaping theory construction and revision, it is the most important one in the historical sequences I have studied. Having said that, it would be hard to find an episode in the History of Science in which some features, even some important features, of the theory were not adopted for reasons other than judgments of empirical adequacy.
As I will argue shortly, the so-called 'tautology' problem in Darwinian selection theory, which philosophers have played a central role in helping resolve, emerged as a consequence of a series of fundamental conceptual and methodological changes in the theory of evolution by natural selection.
It is arguable that none of those changes was mandated by empirical considerations. Hardy , pp. Provine, , chs. From a historian's point of view, nothing could be more suspect. I have denied that the method I am advocating is 'Whiggish', but can one use such an approach and truly avoid that label? Using a detailed case study, I hope to show that one can. The problem I shall focus on is one that has been badly misunderstood, by Karl Popper and others, misunderstandings exploited by 'scientific creationists' and their fellow travelers. But it is a real problem, and we need to begin by formulating it.
In contemporary population genetics, the 'mechanics' of evolutionary theory as Richard Lewontin has called it, the concepts of 'mean fitness' and 'selection coefficient' play a key role. Both claim to be represented by mathematical variables in the mathematical models of the theory. Applying the models - i. Those values are derived from statistical samplings of populations over a number of generations.
The wrongly labeled 'tautology' problem arises from the fact that these relative fitness values are apparently determined by sampling actual populations to determine the actual relative reproductive rates of the different phenotypes. Judgments of relative fitness are based on the actual relative increases and decreases in the frequencies of the allelic combinations under consideration.
But it is these changes in relative frequencies that the models are supposed to explain. And they can only do this if the fitness of a genotype represents something about it that explains these changes in its relative frequency. If it does not, then these models are explanatorily sterile. Now there is a quick answer to this problem that unfortunately does not work. There is a more and a less fundamental problem with this quick answer. The less fundamental problem is that it is completely unclear how one uses this sort of analysis to derive specific, quantifiable fitness values.
If one is simply using guess work, this approach quickly degenerates into the aforementioned sterility - in practice one just keeps adjusting the values until they come within tolerable limits of the values actually found. The more fundamental problem is that we no longer have a single theory, but a potentially infinite number of ad hoc models. After all, the gene combinations that make a horseshoe crab, a scarab beetle, a Caribbean guppy and an African bonobo well-adapted to their environments are utterly different, but the fitness value of some allele relevant to their adaptability may be exactly the same.
A variety of solutions to this worry have been proposed, and it is not fortunately my task today to adjudicate between them. Some have suggested that fitness be conceived as a "reproductive propensity", which given that the mathematical notion of fitness is clearly probabilistic, makes sense. Still others have suggested that it be considered as an "uninterpreted term of the theory", which takes on empirical content only in its explanatory applications Rosenberg, , pp.
Finally Lindley Darden and Joe Cain , pp. What I want to outline today is the way in which studying the history of this subject provides one with a space of philosophical alternatives to the theoretical approach that generates the problem and with a deeper understanding of it. If we return to Charles Darwin's Darwinism, we can see that the theory of evolution by natural selection is free of this problem, but for suspect reasons.
Darwin made no attempt at all to investigate populations empirically to see whether the mechanisms described in the first four chapters of On the origin of species actually produce differential changes in the frequencies of 'small heritable variations', as he claims they will Lennox, , pp. It is unclear why he does not do this, but two reasons are suggested by other aspects of his theoretical perspective. Darwin seemed to think that selection-driven evolution moves with unimaginable slowness in nature - he may thus have assumed that direct evidence would never be available.
It is sometimes wrongly claimed that he thought that evidence of domestic or artificial selection was sufficient to support his theory. It is clear from the following remark, concluding the chapters that presented his theory, that he did not think that. Whether natural selection has really thus acted in nature, in modifying and adapting the various forms of life to their several conditions and stations, must be judged of by the general tenour and balance of evidence given in the following chapters Darwin, , p.
Another possible reason for his not attempting to investigate selection in natural populations is suggested by his theory's most obvious shortcoming, its lack of an account of the origins of variation and of the mechanisms of inheritance. At any rate, Darwin and his followers were well aware that the theory was untestable without a well-verified mechanism of inheritance, since it was by the differential passing on of traits from one generation to the next that evolutionary change was alleged, on his theory, to take place.
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One central project for biology between and was to nail down such a mechanism, and to figure out how to apply information learned in highly controlled experimental settings such as hybrid breeding experiments to natural, uncontrolled populations. The form of genetics that 'caught on' was Mendelian, which used simple statistics and probability theory to analyze the results of experiments involving hybrid crosses, self-fertilization of hybrids and 'back-crosses' of hybrids with pure lines, and to make inferences about the cellular mechanisms producing the resulting ratios of observed traits.
But how to apply this theory to nature? Well, as it turned out, a German Doctor named Weinberg and an English mathematician and cricket lover named Hardy provided a solution, which is incredibly simple. In response to a casual question put to him during a cricket match by the experimentalist R. Punnett, the mathematician G. Hardy pointed out that Mendel's laws, derived from the crossing of pure lines followed by repeated self-fertilization of the resulting hybrids, could be generalized to apply to large randomly breeding populations.
Processes of Life: Essays in the Philosophy of Biology
If we represent the different forms of the gene at the same locus 6 known as different alleles by A and a respectively, that formula will look like this:. The frequencies of the different genotypes can then be represented as follows:. The Hardy-Weinberg Law thus gives us a 'base line' with which we can compare actual changes in frequencies of alleles across generations of reproductive communities.
Deviations from this base line indicate a disruption of this equilibrium of genotypic frequencies across generations.
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There are a number of factors that may lead to such disruptions: a variety of forms of alteration of the genetic material mutation , the migration of new genes into the population which will change the initial frequencies , random changes in frequencies arising from sampling error known as genetic drift and selection favoring one genotype over another. Assuming other disruptive forces have been corrected for or ruled out, population genetics builds into its models the notion that a change in the frequency of a particular genotype is a measure of its relative fitness.
This was a fundamental assumption of the 'genetical theory of natural selection' developed by Ronald Fisher in a book by that name. His name was Sewall Wright. One can think of the relationship between these two brilliant thinkers in the following way: they were studying the same problem, they accepted the theory of the gene, they both saw the problem as a mathematical one, and yet they rejected each others' basic assumptions. Partly because of the intense criticism and rivalry between these two men, both were keenly aware of their assumptions.
But Fisher was well aware of the dangers. After noting "some remarkable resemblances" between his fundamental theorem of natural selection and the second law of thermodynamics, he notes five "profound differences" between them, the second of which is worth quoting. Fitness, although measured by a uniform method, is qualitatively different for every different organism, whereas entropy, like temperature, is taken to have the same meaning for all physical systems Fisher, , pp. Most people are familiar with the basic theory of natural selection.
Organisms vary in a heritable fashion; some variants leave more offspring than others; their characteristics, therefore, are represented at a greater frequency in the next generation. The method I have used is to trace back historically to a point where the problem does not exist, and then work forward historically until one can see it beginning to emerge.
Philosophy of Biology
As in this case, it is often true that at that point, those involved in the scientific debate will be quite self-conscious of problems that a couple of generations later are submerged as unquestioned, unanalyzed presuppositions of the field's common set of concepts and methods. People see the problems, but cannot see what it is about what they are doing that is producing the problems. Nor, while working with those concepts and methods, can they imagine any other way of approaching their subject that will avoid the problems they are facing.
A careful study of the historical genealogy of a philosophical problem can provide a deeper understanding of it, and a richer sense of the theoretical alternatives open to us in solving it. I do not mean to suggest that this is the only worthwhile method for working on problems in the Philosophy of Science. What I hope I have convinced you of is that virtually every problem we work on in the philosophy of science can be illuminated by a phylogenetic reconstruction of that problem. Chicago, Chicago University Press. Princeton, Princeton University Press.
Philosophy of Science, vol. Grene, ed. Stern and E. Sherwood eds. Freeman and Company. Cambridge, Ma. Keller and Lloyd, E. Cambridge, MA. Chicago, University of Chicago Press.
Science, Vol. Savage MD, Rowman and Littlefield.
History and Philosophy of Biology
Kohn ed. Progress and its problems. Berkeley, University of California Press. Horowitz , Thought experiments in science and philosophy , Savage MD, pp. Studies in History and Philosophy of Science, vol. Beatty, J. Philosophy of Science , vol. Fox Keller and E. Lloyd eds. San Francisco, W. Freeman Publishers. I, Princeton, Princeton University Press. Genetics special edition on the birth of Genetics , vol.
All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License. Services on Demand Journal. Whatever people at different times took to be science is considered to be science. The philosopher is not in a position to legislate such matters.
When historians threw the 'internalist' historians of science out of the history departments, they needed a home. Tom Kuhn created one for them, in philosophy departments. You will notice that, despite their different responses to the problem, Giere and Kuhn see the problem, as do many others, in the same way. The history of science is a sort of 'inductive data base' to be used as confirmation for various philosophical views about science.
This is a picture of the relationship between history and philosophy of science I completely reject. My primary goal in this essay is not to argue against this picture, however, but to present an alternative view of the relationship between history of science and philosophy of science. After many years of doing the history and philosophy of biology in a certain way, I spent some time reflecting on what it was I was doing.