From eo12 Mon Jun 09 21:28:56 1997 Path: newsstand.cit.cornell.edu!news.tc.cornell.edu!news3.cac.psu.edu!howland.erols.net!newsxfer3.itd.umich.edu!news1.best.com!kerberos.ediacara.org!there.is.no.cabal From: wilkins Newsgroups: talk.origins Subject: [Draft FAQ] Evolution and Philosophy Part 2 Date: 4 Jun 1997 20:15:15 -0400 Organization: Walter and Eliza Hall Institute of Medical Research Lines: 527 Approved: robomod@ediacara.org Message-ID: NNTP-Posting-Host: kerberos.ediacara.org Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Newsreader: Yet Another NewsWatcher 2.4.0 Continuing the post of the above ================ Why are natural kinds supposed to stay fixed? Summary: species are not eternal types, even though they are natural kinds. Before Lamarck, species were thought to be eternal kinds, and any single organism to have all the necessary and sufficient conditions of being a member of that species. Think of it like this: To be a member of the supporters of a football team, you must have certain characteristics. For argument's sake, suppose they are: 1. paid up membership in the fan club, 2. a personal interest bordering on the obsessive in the fortunes of your team, and 3. ownership of certain items of team identity (caps, flags or books). Anyone who has one, or even two, of these criteria filled may still not be a supporter. You might get your membership from a corporate sponsorship deal in which you have no interest. You might be obsessively fixated due to a pyschological disorder. You might collect things in the hope they become valuable. Each condition is necessary , but only all conditions are sufficient for you to qualify. An organism was thought to need identifying characters - all of them - in order to be a member of the species. And these conditions never changed. 'Football supporter' was an idea that would remain the same even if nobody filled the conditions, or even played football. If something was a species, it could not change, and if it changed, it could not be a species.[note 5] Essentialism Species X Species Y __________ _________ | | | | B | |Criteria | |____|_ | | A, B & | | A _|_|_| | | |__|_|_| | | | | |C|___| |_________| |__|_____| Figure: The difference between essentialist definitions of species, and populational definitions. Not all members of a species may have all the diagnostic traits. This is the kind of view expressed implicitly when a creationist says that such and such a change represents "devolution": a movement away from "pure type". The great evolutionary theorist Ernst Mayr has, following the philosopher Karl Popper, called this "typological essentialism", the opinion that species have essences in some Aristotelian fashion [Mayr 1988]. While the "kinds" mentioned in the Bible (Genesis 1:21-23) are merely observations that progeny resemble parents, that is, that some principle of heredity is active in reproduction, Aristotle held rather that living things are generated in an approximation to a "form" of that species. There is something that represents the perfect dog, for example. [note 6] This view found its way into Christian theology through the rediscovery of Aristotle from the Islamic tradition in the middle ages, primarily through Thomas Aquinas. After the work of the mid-nineteenth century explorers and naturalists, scientists were no longer able to view species in this way. They were much more diverse than that. Not only were species sometimes more different internally than some members were to other species, but it became clear that what was actually common between members of a species was the ability to interbreed (at least, in sexual species). Actually, this view (now called the biological species concept ) predated evolution by some fifty years, deriving from Buffon, who attacked the Linnean system. It meant that seeing species as morphological kinds (that is, as groups of characters of organisms) was no longer scientifically possible. Some, including Darwin, thought on occasions that this meant that species were conventional names given to record observations, but nothing more, and that 'species' were artificial constructions. Others held to the older view that there was something in virtue of which things were members of a species, but that this had nothing to do with their morphology, but with their relations of descent. Of course, if this is all that makes an organism a member of a species, and the variation that is observed is real, then there is nothing in being a species that can prevent a species - or at any rate a part of a species - becoming something different and new. Nothing else makes scientific sense. In this century, the systematist Ernst Mayr (eg, [1970]) has championed the view that what he calls 'typological thinking' has been abandoned by modern biologists in favour of what he calls 'population thinking'. Typology is the view that there are 'types' - unchanging forms that are what makes a species what it is. It derives from the philosophy of Plato, who claimed that true knowledge is knowledge of the Idea (Greek eidos ). Population thinking is a recent development in Western thought - it is the view that aggregates of individuals, groups, have a profile that shows a distribution of characteristics. The well-known 'bell curve' of statistics illustrates this - for any trait of a population you will find a bell curve distribution. Some organisms will be longer or shorter, heavier or lighter, and there will be a mean around which most individuals cluster. Variation is a universal fact about all species. Some parts are located in different environments, and natural selection, genetic drift and happenstance all work to make them different if they are isolated for long enough. Thus are new species created. Enter Michael Ghiselin [1975] and David Hull [1976, 1988], a biologist and philosopher respectively, who proposed that species are not universal types, or classes, but are historical individuals. The name of a species, according to Ghiselin and Hull, is a proper noun, the name of a single and unique individual that has a beginning, a history, and an extinction, and which also has a distribution in space. Homo sapiens is not, on this view, the name of a 'type' of rational animal as Aristotle had it, but the name of a particular lineage of hominoids that happened to develop language and ratiocination. If all humans were extinguished next year, they could never arise again. This view is also hotly debated by philosophers and biologists (cf Gayon [1996]). Mayr [1970] for example thinks that some taxa (eg, families or even orders) are 'grades' which can be arrived at more than once, which the individuality thesis rules out. This is related to the complex and difficult area of the taxonomic methods collectively called cladistics (from the Greek word klados , meaning branch). Cladistics attempts to 'reconstruct the past' [Sober 1988] - recreate phylogeny - using as few theoretical assumptions as possible, on the basis of the present distributions of organismic traits [Panchen 1992]. This deserves an essay on its own, but not by me. Whatever the triumphant view in philosophy, evolutionary notions of species do preclude eternal types, in favour of what the philosophers Hilary Putnam [1975] and Saul Kripke [1972], following the great American philosopher WVO Quine [1969], call 'natural kinds' - things that exist naturally at certain times and places. Like Theseus's ship, they can be changed so much that they are not the same individuals they once were, but this change can happen imperceptibly (at varying rates), as Darwin expected it would. Species are biological entities that change. =================== Does biology just reduce to physics? Summary: biology cannot be reduced to physics, even though all biological entities are physical entities, and nothing more. Group selection is not an accepted evolutionary theory, but group sorting is. The philosophy of science, and criticisms of evolutionary theory in particular, has been driven by the view that physics, or perhaps mathematics, is the very model of a modern scientific discipline. If it ain't like physics in some way, then it ain't science. Unsurprisingly, many biologists weren't happy with this view of what they do as some kind of 'stamp collecting' [note 7]. Ernst Mayr [1970, 1982] attacked this philosophical presumption, especially the idea that biology is just a form of physics, or perhaps chemistry. Philosophers, too, started to make similar attacks [Hull 1974, see Sterelny 1995 for a review]. The view of science of philosophy in the early 60s was reductionist [Nagel 1961]. This meant that in principle the objects and processes of one level of science were made out of the objects of the next level down, ending with subatomic physics. Thus, biology reduced to chemistry, and chemistry reduced to physics. This sort of reduction is called ontological reduction. Those who accept this form of reductionism are called 'physicalists'. Another form of reduction - often confused with this form - is explanatory reduction. This is the view that the properties of one level must be ideally explained as the effects of processes at the next level down. This is roundly denied by many philosophers and biologists, and asserted by many others [eg, Dennett 1995]. Hull argued that it is in principle impossible to reduce, for instance, population genetics to Mendelian genetics, and Mendelian genetics to molecular genetics, because each level is the result of many entities interacting at the lower level, and many entities at the higher level result from a single entity at the lower level: Populational X X X X ^ | | | many above link to many below | V Mendelian X X X X ^ | | | many above link to many below | V Molecular X X X X Hull's problem is called the Problem of the Many to Many, in homage to an old philosophical problem, the Problem of the One and the Many. Many Mendelian genes are made from many DNA molecules, and many populational traits are coded for by many Mendlian genes. Simple reduction will not work. What Williams [1966] called an 'evolutionary gene' is just a unit of heredity that is 'visible' to selection, and it could be an entity at any level - a molcule, a Mendelian gene or even a populational trait. Reduction enters the evolutionary debate in the form of the issue of group selection . In 1962, Wynne-Edwards proposed that some bird populations regulate their clutch size (the number of eggs laid) in hard times to benefit the population as a whole, even though it was detrimental to the 'Darwinian fitness' of the individual birds. Williams [1966] responded with an argument that selection of individuals could account for this and other forms of supposed group selection, and that if group selection occurred at all, it was not very important.[note 8] A decade later, Dawkins [1976] hardened this view into the claim that genes, and genes alone, are the 'units of selection', and that all biological effects in evolution are the result of these 'lower-level' entities. Gene-centrism is not the view that only genes exist, or even that only genes have effects, but that only genes are selected (that is, are evolutionarily important). The way Dawkins put it, as evidenced by the title The Selfish Gene was wrongly interpreted that organisms are irrelvant. More informed analysis developed the view that if evolution-by-selection is generalised, then using Dawkins's own distinction between replicators and vehicles (or Hull's refinement, interactors), then selection can occur at levels above the gene, or even above the organism. This puts the lie to simplistic notions that evolution is defined as a change in allele frequencies. That is what has been called the 'bookkeeping' definition of evolution, and it is true as far as it goes, but it is not all that is interesting about evolution. Few biologists are still simple reductionists, although Williams did write a limited defence of reductionism as a methodological ploy [1985], in which he argued that reduction was the 'null hypothesis' and it was onerous to abandon it. Dennett [1995] claimed that reduction had yet to fail, especially in evolutionary explanations using selection. If evolutionary levels above the gene can be selected, are they adapted? Several have followed Wynne-Edwards on this. Recent versions, though, have moved from the notion that groups are selected, though, in favour of the view that they are sorted, because selection requires that the entity in question replicates, and does so differentially relative to other contenders. This is OK for genes, and arguably for organisms, but species? Even phyla? Groups do not reproduce, they split. Recent work by Gould, Eldredge and Vrba [refs in Sterelny 1995] amends this from species selection to species sorting, what Vrba calls the 'effect hypothesis'. This is a view that now has wide acceptance amongst biologists, including Williams [1992]. Groups are thought to survive extinction events differentially, based on adaptations of their component organisms, so the organisms are adapted, not the groups. ================= Is There Progress and Direction in Evolution? Are there goals? Summary: evolution has no goal, but there are directional trends of a lesser kind. Teleological explanations are more complex than you might think. One of the more common misconceptions, with a history long before Darwin, is that evolution is progressive; that things get more complex and perfect in some way. In fact, this view is attributed more to social and religious attitudes of 18th and 19th century European culture than to any evidence. It was a given that things are getting better and better, every way, every day. This persisted until long after Darwinism, until the middle of this century (eg, Teilhard de Chardin). Even Darwin was ambiguous about it, talking on occasion about 'perfection' as a result of selection. At the time of the 'modern synthesis' [note 9] in the 1940s, the notion of progress was quietly dropped, with a few exceptions like Dobzhansky and Huxley within the synthesis, and Schindewolf and Goldschmidt outside it. Of course, heterodox writers (usually not biologists) like Teilhard and Koestler remained progressionists long after this. But by the 1970s, progress had been abandoned. Recently, the issue has resurfaced, shorn of the mysticism of earlier debates. Biologist JT Bonner argued that there was a rise in complexity of organisms over the long term [1988], and others were arguing for a form of local progress under the terms 'arms race' [Dawkins and Krebs 1979] and 'escalation' [Vermeij 1987]. Gould [1989] felt so strongly about it he was moved to deny that, at least since the Cambrian explosion, there has been any progress at all. Much of the modern debate centres on what counts as 'progress'. Gould [1996] thinks that the apparent trend to complexity is just a matter of random evolution that started at a minimal 'wall' of complexity: Initial early distribution | | Minimum wall of complexity | v | |-| /*\ | | | / \ | | | _/ \___ |_|_|________________________ Later distribution | | Minimum wall of complexity | v | |-| /***\ | | | / \ | | | _ _/ *.._________ |_|_|_________________________ Apparent progress due to a wall restricting where random change can take things. Adapted from Gould 1996. Others [cf Nitecki 1988] claim that there is only progress because any increase over zero is a net increase, and that different measures will give different results. The traditional notion of progress as an increase in perfection or optimality has been abandoned, for it rested on a view that goes back to the late neo-Platonists - the idea that all of reality is arranged in a heirarchy of incxreasing perfection. This is called the scala naturae , and is often referred to the Ladder of Perfection. Modern evolutionary science does not think that the path of evolution is a ladder, although Lamarck did. The current view is best summed up by a phrase of Gould's - evolution is a bush, not a tree. The idea of Progress itself was a late medieval notion, taken from the secularisation of theology, especially from the doctines called 'eschatology' (literally, the 'study of the Last Things') [Ruse 1997]. The 'discovery' of history led to the realisation that biological organisms are historical entities. The view that history was progressive led to the notion that so was the history of life, especially since it led to Man.[note 10] In the nineteenth century, progressivism was rampant, and curiously it always seemed that the ultimate stage was that of the writer, whether it was Marx for the working class, Spencer for the British (mostly the English), or Wagner for the Germans. The first world war came as quite a shock to many, and progress gradually lost its appeal. Biological systems are historical in two ways: they are the result of irreversible processes (ie, they grow and die), and they are contingent. the second point is important if you are thinking about what is science in biology. You can't often repeat an event in biology like speciation (some hybrids can be reformed repeatedly in the lab) and get the same results. What's more, the view called teleology has been dropped by biologists: explanations of what something is for don't say that they are there in order to achieve an end result. It is enough that they are the result of selection. Or is it? Teleology, too, is making a minor comeback. In science, teleology is a way of modelling a system's behaviour by referring to its end-state, or goal. It is an answer to a question about function and purpose. Why do vertebrates have hearts? In order to pump blood around the body to distribute oxygen and nutrients, etc. This is a functional explanation. The function of hearts is to pump blood. In evolution, the question 'why do organisms exhibit adaptation?' is not answered teleologically with 'in order to survive', but historically - 'because those that were less adaptive didn't survive'. However, some forms of teleology are still used, on the understanding that they reduce to historical explanations. It may help to think of a social analogy. We can explain the behaviour of a stock broker teleologically, for a stock broker seeks a goal (the best profit). We cannot explain the behaviour of a stock market , for stock markets have no goals, just outcomes. When Dawkins talks about genes maximising their representation in the gene pool, this is a metaphor not an explanation. Genes just replicate. It happens that those that out-replicate others end up out-surviving them. There is no 'goal' to genetic behaviour. There are two forms of teleological explanation (Lennox 1992). External teleological explanation derives from Plato - a goal is imposed by an agent, a mind, which has intentions and purpose. Internal teleological explanation derives from Aristotle, and is a functional notion. Since Aristotle divided causes up into four kinds - material (the stuff of which a thing is made), formal (its form or structure), efficient (the powers of the causes to achieve the things they achieve) and final (the purpose or end for which a thing exists) - this sort of teleology is really a kind of causal explanation in terms of the value of the thing being explained. This sort of teleology doesn't impact on explanations in terms of efficient causes. You can, according to Aristotle, use both. Evolutionary explanations are most nearly like Aristotle's formal and efficient causes. Any functional explanation begs the further question - what is the reason why that function is important to that organism? - and that begs the even further question - why should that organism exist at all? The answers to these questions depend on the history of the lineage leading to the organism. External teleology is dead in biology, but there is a further important distinction to be made. Mayr [1982: 47-51] distinguished four kinds of explanations that are sometimes called teleology: telenomic (goal-seeking, Aristotle's final causes, 'for-the-sake-of-which' explanations); teleomatic (lawlike behaviour that is not goal-seeking); adapted systems (which are not goal seeking at all, but exist just because they survived); and cosmic teleology (end-directed systems) [cf O'Grady and Brooks 1988]. Only systems that are actively directed by a goal are truly teleological. Most are just teleomatic, and some (eg, genetic programs) are teleonomic (internal teleology), because they seek an end. Goal resulting systems and their relation [Teleomatic systems ] [Teleonomic systems ] [Teleological systems ] [ Adapted systems ] How the four forms of apparent teleology relate. Many criticisms of Darwinism rest on a misunderstanding of the nature of teleology. Systems of biology that are end-seeking are thought to be end-directed, something that Darwinism makes no use of in its models. Outside biology, indeed, outside science, you can use external teleology all you like, but it does not work as an explanation of any phenomena other than those that are in fact the outcomes of agents like stock brokers. And even there, teleology is not always useful, for which stock brokers (or cabal of stockbrokers) desired the goal of the 1987 crash, or the 1930 depression? External teleology is useless in science, and any science that attempts to be teleological will shortly become mysticism. =============== Naturalism - is it necessary? Summary: science must assume that everything can be investigated empirically, but this doesn't force the abandonment of the supernatural, for those who want it. In philosophy, 'naturalism' is the view that an explanation is justified just so far as it rests on evidence of an empirical kind. It has been very active in the philosophy of mind and moral philosophy, and recently as a tool for the 'conceptual hegemony' of science in opposition to the views of some sociologists and historians of science who would relativise worldviews [Rosenberg 1996]. In the creationist-evolution debate, it tends to mean something else - the view that explanations must not take into account the supernatural or spiritual. These two sense overlap to a degree (because evidence of the supernatural is not empirical, but revelatory). Notice, though, that the second sense is a view about what exists, while the former is a view about what can be known in science. If there is a spiritual realm, which is not open to observation, then science cannot use it in explanation, for science is about explaining things that are observed. If science cannot be used to explain things in terms of what it cannot see and test, this doesn't rule out other disciplines using non-natural explanations (like theology). It just means that science cannot use it as it undercuts the very notion of science. There are two ways science cannot be non-naturalistic. It cannot make the assumption that phenomena are themselves non-natural - it has to assume that everything observed is amenable to a naturalistic investigation. Call this methodological naturalism. Science must also avoid non-natural explanations. This is explanatory naturalism. Any explanation that uses a non-natural explanans (thing doing the explaining) fails to be testable. I could propose that some process is the result of an Invisible Pink Unicorn's powers. You can neither falsify nor verify this (in the ordinary senses). The hallmark of science, perhaps the only hallmark, is that explanations are testable. The reason for this lies in what philosophy calls epistemology (from the Greek word for belief, but used in the sense of knowledge - hence, 'the study of knowing'). Epistemologies from Plato to Kant were infalliblistic - a belief was not knowledge if there was any chance it was mistaken. Science, on the other hand, is often wrong, and is constantly revised. Nevertheless, what science delivers is by far the most successful form of knowledge gathering humans have ever developed. The epistemology demanded by science is therefore a falliblistic view of knowing. The basis for this lies in testing. A scientific explanation must be open to any competent investigator to test and evaluate. Revelatory experiences are not universally open to all, and intuitions about the universe are wildly different for different people and cultures, so non-naturalistic explanations are ruled out of the domain of science. A useful way to approach this is to ask what a non-naturalistic explanation would look like. Explanations are equations, of a kind. You explain X by saying it is a Y (and a Z, etc). If a non-natural explanation is to work, it has to put something that is neither empty nor circular on the other side of the equation. What counts as a non-natural explanans? 'Something is non-natural if it isn't natural' is entirely empty until we know how to distinguish between the two. The usual way to define non-natural is that it is not explicable in terms of natural laws; that is, it breaks the causal chain. If we abandon the methodological assumption of naturalism - that everything is open to empirical investigation - we can say that anything not presently explained by scientific laws is non-natural, but that's not what is meant. We can distinguish between our present ignorance and something that's in-principle not scientifically explicable, surely. We want something that is completely outside the course of physical events. But if we had it, could we incorporate it into a scientific explanation? We could obviously not use empirical observations - they depend on the ordinary course of physical processes. So what else is there? The answer is, nothing. Non-natural explanations are not scientific. A final form of naturalism is ontological naturalism. This is the opinion that all that exists (Latin: ens , from which 'ontology' is derived, hence, 'the study of that which exists') is natural. Many scientists are also physicalists. They argue that if we do not need to postulate the reality of non-physical processes for science, then we can conclude that there are no such things. This argument is too quick. The claim that 'if A then B' explains B may be true, but there may also be a C that explains B. Moreover, many things in the physical world are caused by many things together rather than just a few. So, we might say that a physical event is caused both by God and by the physical causes, without being logically inconsistent. Your resolution depends on what you are using as basic assumptions. In science, Ockham's Razor (do not unnecessarily multiply entities in explanation') - also known as parsimony [Sober 1988] - is used to trim as much away as possible in order to achieve the leanest explanation. Extending this outside science is a risky proposition, unless you are willing to make the methodological assumption also work on metaphysics as well as physics. Many are (including myself), but it is not a necessary conclusion from any form of science. In the philosophical doctrine known as moral naturalism, moral systems are explained in terms of the social or biological properties of humans. This is often a Darwinian approach. The point I want to make is that this does not avoid what GE Moore famously called the "Naturalistic Fallacy". You can give a naturalistic explanation of morals without either justifying or invalidating those moral principles. These are two different forms of explanation. So, too, with ontology. You can accept the methodological assumption of naturalism in science without invalidating non-naturalistic ontologies. They just aren't scientific. In my view, ontologies outside science are a matter of personal choice. An as Cicero once said, in matters of taste there is no dispute. In science, there is (legitimate) dispute. Therefore, science is more than a matter of taste. -- John Wilkins, Head of Communication Services, Walter and Eliza Hall Institute of Medical Research [Remove .UNSPAM from header address] It is not enough to succeed. Friends must be seen to have failed. - Capote