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Evolutionary argument against naturalism

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The evolutionary argument against naturalism (EAAN), put forward by philosopher Alvin Plantinga in 1993, suggests that the combination of evolutionary theory and naturalism is self-defeating since if both evolution and naturalism are true, then the probability of having reliable cognitive facilities is low. Plantinga's proposition has drawn the interest of "epistemologists, philosophers of mind, evolutionary biologists, and philosophers of religion".[1]

Plantinga has stated that EAAN is not directed against "the theory of evolution, or the claim that human beings have evolved from simian ancestors, or anything in that neighborhood"[2].

Übersicht

Development of the idea

The idea that "naturalism" undercuts its own justification was put forward by C. S. Lewis in the first edition of his book Miracles in 1947.[3] Similar arguments were advanced by Richard Taylor in Metaphysics[4] and by Stephen Clark in 1984 and 1989.[3] Plantinga proposed his "evolutionary argument against naturalism" in 1991.[4] In the twelfth chapter of his book Warrant and Proper Function, Plantinga developed Lewis' idea,[3] and constructed two formal arguments against evolutionary naturalism,[5] and further developed the idea in an unpublished manuscript entitled "Naturalism Defeated" and in his 2000 book Warranted Christian Belief.[4]

At a Baylor University interdisciplinary conference on "the Role of Naturalism in Science" held in April 2000 at its Michael Polanyi Center dedicated to the study of intelligent design, Plantinga presented a paper on "An Evolutionary Argument Against Naturalism" arguing that "the conjunction of naturalism with current evolutionary theory is self-defeating; the probability that our cognitive faculties are reliable, given naturalism (N) and the proposition that our faculties have arisen by way of the mechanisms suggested by current evolutionary theory (E), is low or inscrutable; either gives one who accepts N&E a defeater for the proposition that his cognitive faculties are reliable, but then also a defeater for anything else he believes, including N&E itself."[6]

Plantinga's argument

Plantinga's argument attempts to show that to combine naturalism and evolution is self-defeating, because, under these assumptions, the probability that humans have reliable cognitive faculties is low or inscrutable.[7]

Plantinga drew comparisons between his ideas and concerns expressed by Charles Darwin in 1881[8] in response to William Graham's claim that natural laws implied purpose. Darwin expressed a belief that the universe was "not the result of chance", but expressed doubts about his own convictions:

But then with me the horrid doubt always arises whether the convictions of man's mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey's mind, if there are any convictions in such a mind?

— Charles Darwin, to William Graham 3 July 1881[9]

Plantinga defines:

  • N as naturalism
  • E as the belief that we human beings have evolved in conformity with current evolutionary theory
  • R as the proposition that our faculties are "reliable", where, roughly, a cognitive faculty is "reliable" if the great bulk of its deliverances are true. He specifically cites a thermometer stuck at 72 degrees placed in an environment which happened to be at 72 degrees as an example of something that is not "reliable" in this sense[10]

and suggests that the conditional probability of R given N and E, or P(R|N&E), is low.[citation needed]

Plantinga's argument begins with the observation that our beliefs can only have evolutionary consequences if they affect behaviour. To put this another way, natural selection does not directly select for true beliefs, but rather for advantageous behaviours. Plantinga distinguishes the various theories of mind-body interaction into four jointly exhaustive categories:

  1. epiphenomenalism, where behaviour is not caused by beliefs. "if this way of thinking is right, beliefs would be invisible to evolution" so P(R/N&E) would be low or inscrutable[11]
  2. Semantic epiphenomenalism, where beliefs have a causative link to behaviour but not by virtue of their semantic content. Under this theory, a belief would be some form of long-term neuronal event[12]. However, on this view P(R|N&E) would be low because the semantic content of beliefs would be invisible to natural selection, and it is semantic content that determines truth-value.
  3. Beliefs are causally efficacious with respect to behaviour, but maladaptive, in which case P(R|N&E) would be low, as R would be selected against.
  4. Beliefs are causally efficacious with respect to behaviour and also adaptive, but they may still be false. Since behaviour is caused by both belief and desire, and desire can lead to false belief, natural selection would have no reason for selecting true but non-adaptive beliefs over false but adaptive beliefs. Thus P(R|N&E) in this case would also be low.[13] Plantinga points out that innumerable belief-desire pairs could account for a given behaviour; for example, that of a prehistoric hominid fleeing a tiger:

Perhaps Paul very much likes the idea of being eaten, but when he sees a tiger, always runs off looking for a better prospect, because he thinks it unlikely the tiger he sees will eat him. This will get his body parts in the right place so far as survival is concerned, without involving much by way of true belief. ... Or perhaps he thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it. ... Clearly there are any number of belief-cum-desire systems that equally fit a given bit of behaviour.[14]

Thus, Plantinga argues, the probability that our minds are reliable under a conjunction of philosophical naturalism and evolution is low or inscrutable. Therefore, to assert that naturalistic evolution is true also asserts that one has a low or unknown probability of being right. This, Plantinga argues, epistemically defeats the belief that naturalistic evolution is true and that ascribing truth to naturalism and evolution is internally dubious or inconsistent.[15]

Plantinga states that he is not attacking the theory of evolution,[16] which only yields the self-contradiction when connected with philosophical naturalism but is not equally inconsistent with theism. Theism may accept the scientific description of evolutionary processes but also allow for the presence of a God capable of creating a universe whose physical properties produce reliable human cognitive faculties, even though the direct physical cause thereof is undirected (see, for example, the philosophical position known as theistic evolution) [17].

Responses

Fitelson and Sober's response

Branden Fitelson of the University of California, Berkeley and Elliott Sober of the University of Wisconsin-Madison criticised the argument in 1998.[5] Firstly, they criticise his use of a Bayesian framework, suggesting that it would apply equally well to "any non-deterministic theory in the natural sciences." Secondly, they criticise Plantinga's presentation of the mechanisms of evolution and his analysis of the relation between belief and behavior: even though Plantinga may be correct that natural selection only "cares" about behaviour and not about the truth or falsity of beliefs, it still does not follow that true and false beliefs are equally likely to evolve.

Finally, they suggest that Plantinga does not show that proponents of metaphysical naturalism should a priori doubt all of their beliefs. This is because the argument rests in part on the idea that E&N together defeat proposition R (i.e., that evolution combined with philosophical naturalism make it unlikely that the great bulk of our beliefs are true). From this defeater Plantinga concludes that proponents of E&N should not have confidence in any of their beliefs, including their belief in E&N. But "[e]ven if E&N defeats the claim that 'at least 90% of our beliefs are true,' it does not follow that E&N also defeats the more modest claim that 'at least 50% of our beliefs are true'." In other words, according to Fitelson and Sober, Plantinga needs to show not only that our beliefs could be false but adaptive, but that they could be pervasively so.

Robbins' response

Indiana University South Bend Professor of Philosophy J. Wesley Robbins contends that Plantinga's argument applies only to Cartesian philosophy of minds but not to pragmatist philosophies of mind. Robbins' argument, stated roughly, is that while in a Cartesian mind beliefs can be identified with no reference to the environmental factors that caused them, in a pragmatic mind they are identifiable only with reference to those factors. That is to say, in a pragmatic mind beliefs would not even exist if their holder had not come in contact with external belief-producing phenomena in the first place.[18]

Naturalism Defeated?

A collection of essays entitled Naturalism Defeated? (2002) contains responses by 11 philosophers to EAAN.[19] The responsive essays include the following:

  • William Ramsey argues that Plantinga “overlooks the most sensible way . . . to get clear on how truth can be a property of beliefs that bestows an advantage on cognitive systems”. He also argues the commonsensical point that since some of our cognitive faculties are slightly unreliable, isn't E&N better suited than theism to explain this imperfection?
  • Jerry Fodor argues that there is a plausible historical scenario according to which our minds were selected because their cognitive mechanisms produced, by and large, adaptive true beliefs.
  • Evan Fales argues that Plantinga has not demonstrated that the reliability of our cognitive faculties is improbable, given Neo-Darwinism, and emphasizes that “if Plantinga’s argument fails here, then he will not have shown that [N&E] is probabilistically incoherent.” Also, given how expensive (in biological terms) our brain is, and considering we are rather unremarkable creatures apart from our brains, it would be quite improbable that our rational faculties be selected if unreliable. "Most of our eggs are in that basket," says Fales.

    Fales argues along the same as Robbins: take a mental representation, of heat, for example. Only so long as it is really caused by heat can we call it a mental representation of heat; otherwise, it is not at all a mental representation, of heat or of anything else: "so long as representations [semantics] are causally linked to the world via the syntactic structures in the brain to which they correspond [syntax], this will guarantee that syntax maps onto semantics in a generally truth-preserving way."[20] This is a direct response to one of Plantinga's scenarios where, according to Plantinga, false-belief generating mechanisms may have been naturally selected.

  • Michael Bergmann suggests that Thomas Reid offers the resources for a commonsense (Reidian) defense of naturalism against EAAN.
  • Ernest Sosa draws on features of Descartes’ epistemology to argue that while “[i]ssues of circularity do arise as to how we can rationally and knowledgeably adopt [an epistemically propitious] view about our own epistemic powers,” nonetheless, “these problems are not exclusive to naturalism.”
  • James Van Cleve suggests that even if the probability thesis is true, this need not deliver an undefeated defeater to R, and that even if one has a defeater for R, why does it follow that one has a defeater for everything?
  • Richard Otte thinks the argument “ignores other information we have that would make R likely.”
  • William Talbott suggests that “Plantinga has misunderstood the role of undercutting defeaters in reasoning.”
  • Trenton Merricks says that “in general, inferences from low or inscrutable conditional probability to defeat are unjustified.”
  • William Alston argues that the claim that P(R/N&E) is low is poorly supported; if, instead, it is inscrutable, this has no clear relevance to the claim that (1) is a defeater for N&E.

Naturalism Defeated? also included Plantinga's replies to both the critical responses contained in the book and to some objections raised by others, including Fitelson & Sober:

  • Plantinga expounds the notion of Rationality Defeaters in terms of his theory of warrant and proper function and distinguishes between Humean Defeaters and Purely Alethic Defeaters, suggesting that although a Naturalist will continue to assume R "but (if he reflects on the matter) he will also think, sadly enough, that what he can't help believing is unlikely to be true."[21]
  • Plantinga argues that semantic epiphenomenalism is very likely on N&E because, if materialism is true, beliefs would have to be neurophysiological events whose propositional content cannot plausibly enter the causal chain.[22] He also suggests that the reliability of a cognitive process requires the truth of a substantial proportion of the beliefs it produces, and that a process which delivered beliefs whose probability of truth was in the neighbourhood of 0.5 would have a vanishingly unlikely chance of producing (say) 1000 beliefs 75% of which were true.
  • In The conditionalisation problem, Plantinga discusses the possibility that N+ i.e. "Naturalism plus R," could be a basic belief thus staving off defeat of R, suggesting that this procedure cannot be right in general otherwise every defeater could automatically be defeated, introducing the term "defeater-deflector[23] " and initially exploring the conditions under which a defeater-deflector can be valid.

Ruse's response

In a chapter titled 'The New Creationism: Its Philosophical Dimension', in The Cultures of Creationism, philosopher of science Michael Ruse discusses EAAN, making the following points:

  • That the EAAN conflates methodological & metaphysical naturalism.[24]
  • That Plantinga "fudges" between "the world as we can in some sense discover" and "metaphysical reality", and that "[o]nce this distinction is made, Plantinga's refutation of naturalism no longer seems so threatening."[25]
  • That "[i]t is certainly the case that organisms are sometimes deceived about the world of appearances and that this includes humans. Sometimes we are systematically deceived, as instructors in elementary psychology classes delight in demonstrating. Moreover, evolution can often give good reasons as to why we are deceived." He continues that Plantinga's hypothesised deceptions are "not how evolution's deceptions work."[25]

Ruse concludes his discussion of the EAAN by stating:

To be honest even if Plantinga's argument [the EAAN] worked, I would still want to know where theism ends (and what form theism must take) and where science can take over. Is it the case that evolution necessarily cannot function, or it is merely false and in another God-created world it might have held in some way — and if so, in what way? Plantinga has certainly not shown that theist must be a creationist, even though his own form of theism is creationism.[26]

See also

Notes

  1. ^ Beilby(2002) pvii
  2. ^ Beilby(2002) p1
  3. ^ a b c Nathan, N.M.L. (1997). "Naturalism and Self-Defeat: Plantinga's Version". Religious Studies. 33 (2): 135–42.
  4. ^ a b c Beilby(2002) p. ix
  5. ^ a b Fitelson, Branden (1998). "Plantinga's Probability Arguments Against Evolutionary Naturalism" (PDF). Pacific Philosophical Quarterly. 79 (2): 115–129. doi:10.1111/1468-0114.00053. Retrieved 2007-03-06. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ William A. Dembski (2000). "Intelligent Design at Baylor University". Retrieved 2009-05-23. The Nature of Nature, An Interdisciplinary Conference on the Role of Naturalism in Science
  7. ^ Plantinga, Alvin (1993). Warrant and Proper Function. New York: Oxford University Press. doi:10.1093/0195078640.001.0001. ISBN 0195078640.
  8. ^ Beilby p.3
  9. ^ "Darwin Correspondence Project - Letter 13230 — Darwin, C. R. to Graham, William, 3 July 1881". Retrieved 2009-05-15.
  10. ^ Beilby(2002) p 2.
  11. ^ Beilby(2002) p 6
  12. ^ Beilby(2002) pp 6-7. Here Plantinga cites Robert Cummins as suggesting that this is the "received view"
  13. ^ Beilby(2002) pp8-9
  14. ^ Plantinga, Warrant and Proper Function, pp. 225-226 <http://dx.doi.org/10.1093/0195078640.001.0001>
  15. ^ Beilby p.1
  16. ^ Beilby(2002) p1
  17. ^ Beilby p.1-2
  18. ^ Robbins, J. Wesley (1994). "Is Naturalism Irrational?". Faith and Philosophy. 11 (2): 255–59.
  19. ^ Summarised, unless otherwised referenced, from the review by John F Post
  20. ^ Fales, Evan (1996). "Plantinga's Case against Naturalistic Epistemology". Philosophy of Science. 63 (3): 432–51., cited in Naturalism Defeated? as being an earlier version of Fales' response.
  21. ^ Beilby(2002) p 211
  22. ^ Beilby(2002) pp211-213 - he says that these arguments are "related in ways that are not entirely clear to arguments made by Jaegwon Kim in Mind in a Physical World
  23. ^ ie something that prevents D (a supposed Defeater) from being a defeater in the first place, as opposed to a defeater-defeater which defeats D Beilby(2002) p224.
  24. ^ Coleman(2004) p187
  25. ^ a b Coleman(2004) p188
  26. ^ Coleman(2004) p190

References

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