Posted By Thomas Perez. August 10, 2010 at 9:34pm. Copyright 2010.
Inferences to the Best Explanation/Deductive Design Arguments: Schema 3
Some philosophers of science claim that in a wide variety of scientific cases we employ an “inference to the best explanation” (IBE). The basic idea is that if one among a number of competing candidate explanations is overall superior to others in significant respects — enhanced likelihood, explanatory power and scope, causal adequacy, plausibility, evidential support, fit with already-accepted theories, predictiveness, fruitfulness, precision, unifying power, and the like — then we are warranted in (rovisionally) accepting that candidate as the right explanation given the evidence in question. Some advocates see design arguments as inferences to the best explanation, taking design explanations — whatever their weaknesses — as prima facie superior to chance, necessity, chance-driven evolution, or whatever.
The name (IBE) and an especially important early discussion came from Gilbert Harmon (1965). Perhaps the best known more recent work is that of Peter Lipton (1991, 2004, 2006). Lipton’s initial description comes in his (1991, 58):
According to Inference to the best Explanation … given our data and our background beliefs, we infer what would if true, provide the best of the competing explanations we can generate of those data (so long as the best is good enough for us to make any inference at all).
Extracting a general schema from that description, and deploying it in the current case would give us the following:
- Some things in nature (or nature itself, the cosmos) exhibit exquisite complexity, delicate adjustment of means to ends (and other relevant R characteristics).
- The hypothesis that those characteristics are products of deliberate, intentional design (Design Hypothesis) would adequately explain them.
- In fact, the hypothesis that those characteristics are products of deliberate, intentional design (Design Hypothesis) is the best available overall explanation of them.
- Some things in nature (or nature itself, the cosmos) are products of deliberate, intentional design (i.e., the Design Hypothesis is likely true).
In arguments of this type, superior explanatory virtues of a theory are taken as constituting decisive epistemic support for theory acceptability, warranted belief of the theory, and likely truth of the theory. There are, of course, multitudes of purported explanatory, epistemic virtues, including the incomplete list a couple paragraphs back (and lists of such have evolved over time). Assessing hypotheses in terms of such virtues is frequently contentious, depending, as it does, on perceptions of ill-defined characteristics, differences in background conceptual stances, and the like. Still, in general we frequently manage rough and ready resolutions.
One key underlying structure in this context is typically traced to Peirce’s notion of abduction. Suppose that some otherwise surprising fact e would be a reasonably expectable occurrence were hypothesis h true. That, Peirce argued, would constitute at least some provisional reason for thinking that h might actually be true. Peirce’s own characterization was as follows (Peirce 1955, 151):
- The surprising fact, C, is observed.
- But if A were true, C would be a matter of course.
- There is reason to suspect that A is true.
Without going into the very familiar details, Darwinian processes fueled by undesigned, unplanned, chance variations would, it is argued, over time produce organisms exquisitely adapted to their environmental niches. And since many of the characteristics traditionally cited as evidences of design just were various adaptations, evolution would thus produce entities exactly fitting traditional criteria of design. Darwinian evolution, then, unaided by intention or intervention could account for the existence of many (perhaps all) of the Rs which we in fact find in nature. That was — and is — widely taken as meaning that arguments depending either upon design’s explanatory superiority or upon specific causal or explanatory gaps would be weakened — perhaps fatally.
That was—and is—widely taken as meaning that design arguments depending upon specific biological gaps would be weakened—perhaps fatally. Thus Darwin in a very famous passage from his autobiography:
The old argument of design in nature, as given by Paley, which formerly seemed to me so conclusive, fails, now that the law of natural selection had been discovered. We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man. There seems to be no more design in the variability of organic beings and in the action of natural selection, than in the course which the wind blows. Everything in nature is the result of fixed laws. (Darwin 1887, 279)
Premise (10) — not to mention the earlier (6) — would thus look to simply be false. What had earlier appeared to be purpose (requiring intent) was now apparently revealed as mere unintended but successful and preserved function.
Of course, relevant premises being false merely undercuts the relevant schemas in present form — it does not necessarily refute either the basic design intuition or other forms of design arguments. But some critics take a much stronger line here. Richard Dawkins, for instance, subtitles one of his books: “Why the evidence of evolution reveals a universe without design” (Dawkins, 1987). Typically underlying claims of this sort is the belief that Darwinian evolution, by providing a relevant account of the origin and development of adaptation, diversity, and the like, has explained away the alleged design in the biological realm — and an attendant designer — in much the same way that kinetic theory has explained away caloric. Indeed, this is a dominant idea underlying current responses to design arguments. However, undercutting and explaining away are not necessarily the same thing, and exactly what explaining away might mean, and what a successful explaining away might require are typically not clearly specified. So before continuing, we need clarity concerning some relevant conceptual landscape.
Further Contemporary Design Discussions
It was recognized centuries back that conditions necessary for the flourishing of life were fairly tightly constrained (making the move to design in natural conditions and laws inherently attractive), but not until quite recent times has it been revealed through science itself just how wildly tight the constraints actually are, and just how many separate things have to converge, each within a miniscule value interval. For instance, here are two examples taken from Robin Collins:
1. If the initial explosion of the big bang had differed in strength by as little as one part in 1060, the universe would have either quickly collapsed back on itself, or expanded too rapidly for stars to form. In either case, life would be impossible. (As John Jefferson Davis points out, an accuracy of one part in 1060 can be compared to firing a bullet at a one-inch target on the other side of the observable universe, twenty billion light years away, and hitting the target.) 3. Calculations by Brandon Carter show that if gravity had been stronger or weaker by one part in 1040, then life-sustaining stars like the sun could not exist. This would most likely make life impossible. (Collins 1999, 49.)
In light of these and other examples, Collins remarks that “Almost everything about the basic structure of the universe … is balanced on a razor’s edge for life to occur.” (Collins 1999, 48).
There is some disagreement over just how many such independent factors there are, but by some counts there are over 100, although not all requiring the above degree of precision. But the apparent probability of all the necessary conditions sufficient to allow just the formation of planets (let alone life) coming together just by chance is utterly outrageously tiny—by Roger Penrose’s calculation, the probability of chance alone producing cosmoi capable of producing planets is 1 in 10 raised in turn to the 10123 (Penrose 1990, 343–4). With respect to key enzymes occurring by chance, astrophysicist Fred Hoyle throws around numbers like 10-40000 (Hoyle 1982, 4–5). (Although there is no consensus, some, following e.g., Emile Borel, suggest that a probability of occurrence of less than 10-50 can be taken as equivalent to practical impossibility.) Apparently crushing improbabilities of that order tied to the apparent value of a life-permitting (or intelligence-permitting) universe has given rise to cosmic fine-tuning arguments for design, according to which improbable fine-tuning of the cosmos for life and intelligence is taken as empirical evidence of design, purpose, and deliberate intent. In fact, the tighter the constraints, the more reasonable it becomes to see design in the conditions meeting those constraints. Other things being equal, deliberate, intentional design would constitute a plausible explanation for a universe like ours existing against the odds and out of all the myriad possible life-precluding or life-hampering universes.
The issue once again turns in part upon the availability of alternative explanations. In this case, there are two discussed historically—necessity and chance. It could be claimed (a) that a cosmos having the appearance of being designed had to exist, that a universe like ours was virtually inevitable, or, more circumspectly, (b) that any cosmos in which intelligent beings found themselves would have to have some threshhold level of order and complexity, that being a necessary condition for the existence of any such observing intelligent beings to begin with. The former never gained substantial influence. The latter would be a version of a (Weak) Cosmological Anthropic Principle. While trivially true, such a principle has no explanatory power, and does not constitute a substantive alternative explanation. And although historically the idea of sheer chance production of a life-hospitable cosmos was occasionally injected into the discussion and although that was no doubt logically possible in some technical sense, few saw that suggestion as attractive. Barring any viable alternative, cosmic fine-tuning via deliberate agency seems to many to constitute a live candidate for a design argument.
There have, however, been recent attempts to construct viable alternatives. The traditional method of overcoming prohibitive single-throw odds has been to multiply the number of tries—much as one can overcome the odds against throwing a double six given enough throws of the dice. In general, a state space of possibilities, no matter how extensive, can be saturated via enough separate random tries, so that any value-points in the space will eventually be discovered. Hume discussed this type of strategy for countering cosmic design arguments, and current many-universe theories are sometimes intended to function in similar manner, thus undercutting cosmic fine-tuning arguments. The specific idea is that if there are enough universes of randomly varying types, at least some of them will just by chance meet the tight requirements for life and consciousness, such a location being where any intelligences would inescapably find themselves (for reasons sketched above), were there any selves to do any finding and thus no appeal to design (it is claimed) would appear necessary to explain that fine-tuning. There are currently a number of proposed theoretical bases for the existence of multiple universes.
However, there are a number of serious difficulties confronting many-universe theories, three of which are, very briefly, as follows. First, such theories typically involve vast assemblages of other universes which are utterly inaccessible from this one, and whose very existences are thus massively speculative—perhaps incurably so. Second, Ockham would have had some things to say here about many-universe theories vs. design—as do physicists Paul Davies:
Invoking an infinite number of other universes just to explain the apparent contrivances of the one we see is pretty drastic, and in stark conflict with Occam’s razor. (Davies 1995, 121)
and Edward Harrison:
Take your choice: blind chance that requires multitudes of universes, or design that requires only one. (Harrison 1985, 252)
Third, it is not even clear that collections of such universes…even granting their existence and relevance—perform their claimed design-eroding task. This particular type of attempt may fail conditions (a), (b), (c), and (e) above. Much depends upon the type of collection, its structure, etc.—none of which we have the slightest clue about.
There are serious questions surrounding cosmic fine-tuning arguments as well. As noted earlier, with gapless cases of indirect design the full evidential weight would rest upon the mind-suggestiveness of the Rs themselves and upon the unlikelihood of the tightly-constrained requisite conditions themselves being products of either chance or necessity. (Basing them on even deeper laws and conditions will generate a regress which only chance, necessity or agency can halt.) But given the numbers, the exquisiteness of the fitness for life and the generally conceded value of life, consciousness, etc., some even of those staunchly resistant to supernatural explanations find themselves impelled to seek for plausible alternative explanations. Thus, Francis Crick toys with terms like ‘miracle’, Frederick Hoyle refers to a superintellect ‘monkeying’ with physics, and Andrei Linde raises the possibility of our cosmos itself being a product of design—by some supertechnological alien culture. The character of such proposals is itself testimony to the prima facie plausibility of fine-tuning cases and would of course have substantive implications for whether attempts to explain away met condition (e). This whole area is enveloped in spirited contemporary debate—but that fine-tuning arguments do represent a currently live possibility for empirically updated cosmic design arguments is not an uncommon view.
The “Intelligent Design” (ID) Movement
A high-profile development in design arguments over the past decade or so involves what has come to be known as the “Intelligent Design” (ID) movement. Although there are variants and unclarities, the movement involves efforts to construct design arguments taking cognizance of various contemporary scientific developments (primarily in biology, biochemistry, mathematics and cosmology)—developments which, as most ID advocates see it, both reveal the inadequacy of mainstream (naturalistic Darwinian) explanatory accounts (condition (a)) and offer compelling evidence for design in nature at some level (condition (e) again). ID advocates have tried to establish not only the rational cogency of design cases but have pushed ID as legitimately scientific by trying both to define relevant Rs with adequate empirical precision and to construct design arguments with suitable scientific/mathematical rigor.
ID advocates propose three specialized Rs—irreducible complexity, specified complexity and information. Although distinctions are sometimes blurred here, while ID arguments involving each of those Rs tend to be gap arguments, an additional focus on mind-reflective aspects of nature is typically more visible in ID arguments citing specified complexity and information than in arguments citing irreducible complexity. Gaps are also a defining feature of the “explanatory filter” frequently endorsed by ID advocates.
The movement has elicited vociferous criticism and opposition. Opponents have pressed a number of objections against ID including, inter alia contentions that ID advocates have simply gotten the relevant science wrong, that even where the science is right the empirical evidences cited by design advocates do not, in fact, constitute substantive grounds for design conclusions, that the existence of demonstrably superior alternative explanations for the phenomena cited (Darwinian, many-universes, etc.) undercuts the cogency of ID cases, and that design theories are not legitimate science, but are just disguised creationism, God-of-the-gaps arguments, religiously motivated, etc.
I will not pursue that dispute here except to note that even if the case is made that ID arguments could not count as proper science (and arguments for that more general claim are controversial), that would not in itself demonstrate some deeper rational or inferential defect in design arguments as such. Science need not be seen as exhausting the space of legitimate conclusions from empirical data.
But the floods of vitriol in the current ID discussion suggest that much more than the propriety of selected inferences from particular empirical evidences is at issue. Although there is indeed much more that energizes the squabble on both sides (political, cultural, philosophical and, in some instances, religious) there is one further aspect of the ID attempt which ties in here, but which is also relevant to one final larger question.
The Persistence of Design Thinking
That question is: why do design arguments remain so durable if empirical evidence is inferentially ambiguous, the arguments logically controversial, and the conclusions vociferously disputed? One possibility is that they really are better arguments than most philosophical critics concede. Another possibility is that design intuitions do not rest upon inferences at all. The situation may parallel that of the existence of an external world, the existence of other minds, and a number of other familiar matters. The 18th century Scottish Common Sense philosopher Thomas Reid (and his contemporary followers) argued that we are simply so constructed that in certain normally-realized experiential circumstances we simply find that we in fact have involuntary convictions about such a world, about other minds, and so forth. That would explain why historical philosophical attempts to reconstruct the arguments by which such beliefs either arose or were justified were such notorious failures—failures in the face of which ordinary belief nonetheless proceeded happily and helplessly onward. If a similar involuntary belief-producing mechanism operated with respect to intuitions of design, that would similarly explain why argumentative attempts have been less than universally compelling but yet why design ideas fail to disappear despite the purported failure of such arguments—persisting even in the case of Darwin (at intervals up to his death), and of the contemporary biologists Crick thought had to be on their guard against design interpretations.
A number of prominent figures historically in fact held that we could determine more or less perceptually that various things in nature were candidates for design attributions—that they were in the requisite respects design-like. Some held that we could perceptually identify some things as more than mere candidates for design. For instance, according to William Whewell:
When we collect design and purpose from the arrangements of the universe, we do not arrive at our conclusion by a train of deductive reasoning, but by the conviction which such combinations as we perceive, immediately and directly impress upon the mind. ‘Design must have a designer.’ But such a principle can be of no avail to one whom the contemplation or the description of the world does not impress with the perception of design. It is not therefore at the end but at the beginning of our syllogism, not among remote conclusions, but among original principles, that we must place the truth, that such arrangements, manifestations, and proceedings as we behold about us imply a Being endowed with consciousness, design, and will, from whom they proceed. (Whewell 1834, 344)
The world, says Whewell, impresses us with a perception of design. Thomas Reid also held a view in this region, and Hume’s Cleanthes made suggestions in this direction.
If something like that were the operative process, then the ID movement, in trying to forge a scientific link to design in the sense of inferences from empirically determined evidences would be misconstructing the actual basis for design belief, as would be design arguments more generally. It is perhaps telling, in this regard, that scientific theorizing typically involves substantial creativity and that the resultant theories are typically novel and unexpected. Design intuitions, however, do not seem to emerge as novel construals from creative grappling with data, but are embedded in our thinking nearly naturally—so much so that, again, Crick thinks that biologists have to be immunized against it. Indeed, design structures seem to be part of the very fabric of science itself. According to physicist Paul Davies
Science began as an outgrowth of theology, and all scientists, whether atheists or theists … accept an essentially theological worldview. (Davies 1995, 138)
All of that suggests to some that we are dealing with a different category of belief formation and acquisition. And it also suggests that design thinking may be natural to our sorts of intellects.
- Argyll, George Douglas Campbell, 8th Duke of, 1885. “What is science?” in Good Words, (April): 236–45.
- Babbage, Charles, 1838. Ninth Bridgewater Treatise: A Fragment, London: J. Murray.
- Behe, Michael, 1996. Darwin’s Black Box, New York: Free Press.
- Boyle, Robert, 1685–6. Free Inquiry into the Vulgarly Receiv’d Notions of Nature, in Hall 1965, pp. 150–153.
- Broad, C.D., 1925. The Mind and its Place in Nature, London: Kegan Paul.
- Chesterton, G.K., 1908. “Ethics of Elfland,” in Orthodoxy, New York: John Lane, pp. 106–7.
- Collins, Robin, 1999. “A Scientific Argument for the Existence of God,” in Murray 1999, pp. 47–75.
- Crick, Francis, 1988. What Mad Pursuit, New York: Basic.
- Darwin, Charles, 1859 . On the Origin of Species, Facsimile first edition, Cambridge, MA: Harvard University Press.
- Darwin, Charles, 1887. Life and Letters of Charles Darwin, Vol. 1, Francis Darwin (ed.), New York: D. Appleton.
- –––, 1902 . The Life of Charles Darwin, Francis Darwin (ed.), London: Senate.
- –––, 1987. Charles Darwin’s Notebooks, 1836–1844. Transcribed and edited by Paul Barrett, Peter Gautrey, Sandra Herbert, Dave Kohn and Sydney Smith, Ithaca: Cornell.
- Davies, Paul, 1995. Are We Alone?, New York: Basic.
- Davis, John Jefferson, 1987. “The Design Argument, cosmic ‘fine-tuning,’ and the Anthropic Principle,” The International Journal of Philosophy of Religion, 22: 139–150.
- Dawkins, Richard, 1987. Blind Watchmaker, New York: Norton.
- Dembski, William, 1998. The Design Inference, Cambridge: Cambridge University Press.
- –––, 2002. No Free Lunch, Lanham: Rowman and Littlefield.
- Edwards, Jonathan, 1980. The Works of Jonathan Edwards Wallace Anderson (ed.), Volume 6: Scientific and Philosophical Writings, New Haven: Yale University Press.
- Ellis, G. and G. Brundrit, 1979. “Life in the Infinite Universe,” Quarterly Journal of the Royal Astronomical Society, 20: 37–41.
- Fitelson, Brandon, 2007. “Likelihood, Bayesianism, and Relational Confirmation,” Synthese, 156: 473-489 –101.
- Foster, John, 1982–3. “Induction, Explanation and Natural Necessity,” Proceedings of the Aristotelian Society, 83: 87–101.
- Foster, John, 1985. A. J. Ayer, London: Routledge & Kegan Paul.
- Gillispie, Neal C., 1990. “Divine Design and the Industrial Revolution: William Paley’s Abortive Reform of Natural Theology,” Isis, 81: 213–229.
- Glass, Marvin and Julian Wolfe, 1986. “Paley’s Design Argument for God,” Sophia, 25(2): 17–19.
- Hacking, Ian, 1987. “Inverse Gambler’s Fallacy: the argument from design,” Mind, 96: 331–340.
- Haldane, J.B.S., 1928. “Possible Worlds,” in Possible Worlds, New York: Harper & Brothers.
- Hall, Marie Boas, 1965. Robert Boyle on Natural Philosophy, Bloomington: Indiana University.
- Harmon, Gilbert, 1965. “Inference to the Best Explanation,” Philosophical Review, 74: 88-95–101.
- Harrison, Edward, 1985. Masks of the Universe, New York: Macmillan.
- Howson, Colin and Peter Urbach, 1989. Scientific Reasoning: The Bayesian Approach, LaSalle: Open Court.
- Hoyle, Frederick, 1982. “The Universe: Past and Present Reflections,” Annual Review of Astronomy and Astrophysics, 20: 1–35.
- Hume, David, 1779 . Dialogues Concerning Natural Religion, Richard Popkin (ed.), Indianapolis: Hackett.
- Johnson, Phillip, 1991. Darwin on Trial, Downers Grove: InterVarsity.
- Kingsley, Charles, 1890. Water Babies, London: Macmillan.
- Lenoir, Timothy, 1982. Strategy of Life, Chicago: University of Chicago Press.
- Leslie, John, 1989. Universes, London and New York: Routledge.
- Lipton, Peter,1999. Inference to the Best Explanation . 1st Edition. London: Routledge.
- –––, 2004. Inference to the Best Explanation . 2nd Edition. London: Routledge.
- –––, 2006. “Wouldn’t it be Lovely: Explanation and scientific realism,” Metascience, 14: 331-361. Review Symposium: James Ladyman, Igor Douven, Bas van Frassen and Lipton. (Lipton’s contribution is 353-361) –101.
- MacLeay, William Sharp, 1819–21. Horae Entomologicae, in Linnean Transactions, 14: 395–517.
- Manson, Neil (ed.), 2003. God and Design: The teleological argument and modern science, New York: Routledge.
- McPherson, Thomas, 1965. The Philosophy of Religion, London: Van Nostrand.
- Meyer, Stephen, 1998. “DNA by Design: An inference to the best explanation for the origin of biological information,” Rhetoric & Public Affairs, 1: 519-555–101.
- Murray, Michael (ed.), 1999. Reason for the Hope Within, Grand Rapids: Eerdmans.
- Nuovo, Victor, 1992. “Rethinking Paley” Synthese, 91: 29–51.
- Paley, William, 1802. Natural Theology, Indianapolis: Bobbs-Merrill, 1963.
- Peirce, Charles S., 1955. Philosophical Writings of Peirce, Justus Buchler (ed.), New York: Dover.
- Penrose, Roger, 1990. The Emperor’s New Mind, Oxford: Oxford University Press.
- Priestley, Joseph, 1795. Letters to a Philosophical Unbeliever, Philadelphia: Dobson.
- Ratzsch, Del, 2001. Nature, Design and Science, Albany: SUNY Press.
- –––, 2003. “Perceiving Design,” in Manson 2003, pp. 124–144.
- –––, 2005. “Saturation, World Ensembles and Design,” Faith and Philosophy, 22(5): 667–686.
- Roget, Peter Mark, 1834. Animal and Vegetable Physiology Considered with Reference to Natural Theology, London: William Pickering.
- Sober, Elliott, 1993. Philosophy of Biology, Boulder: Westview.
- –––, 2003. “The Design Argument” in Manson 2003, pp. 27–54.
- –––, 2009. Core Questions in Philosophy . 5th Edition. Upper Saddle River, NJ: Pearson.
- Steel, Daniel, 2007. “Bayesian Confirmation Theory and the Likelihood Principle,” Synthese, 156: 53-77–101.
- Swinburne, Richard, 1991. The Existence of God, New York: Clarendon.
- Whewell, William, 1834. Astronomy and General Physics Considered with Reference to Natural Theology, London: William Pickering.
- –, 1853. Of the Plurality of Worlds, 3rd edition, Chicago: University of Chicago Press, 2001.
Natural Theology; or, Evidences of the Existence and Attributes of the Deity, by William Paley.
Dictionary of the History of Ideas—The Design Argument, by Frederick Ferré, maintained by The Electronic Text Center at the University of Virginia Library.
Design Arguments for the Existence of God, by Kenneth Einar Himma (Seattle Pacific University), hosted by the Internet Encyclopedia of Philosophy.
The Teleological Argument and the Anthropic Principle, by William Lane Craig (Talbot School of Theology), hosted by Leadership U.
Anthropic-Principle.com, maintained by Nick Bostrom (Oxford University).
Robin Collins’s Fine-Tuning Website, maintained by Robin Collins (Messiah College).
The Universe, Design, and Fine Tuning, by Michael Sudduth, lecturer, San Francisco State University.