Friday, December 13, 2013

Review of Naturalism: A Critical Analysis edited by William Lane Craig and J.P. Moreland (Part 3)

This is part three of a series of articles on the book Naturalism: A Critical Analysis.  You can find part one and part two in my blog archive.

Chapter 3: The Incompatibility of Naturalism and Scientific Realism
by Robert C. Koons

Robert Koons continues the book's assault on naturalism by arguing against the compatibility of naturalism and scientific realism.  Scientific realism is simply the position that the methods and findings of science uncover objective information about really existing entities in the world.  The reason a telescope displays a bright patch of light when pointed in a certain direction in space, for example, is because there's a ball of burning energy out there causing the telescope to display what it does.  Many naturalists, as far as I can tell, are strongly motivated toward naturalism precisely because they think scientific realism is the correct view of reality, and they think naturalism bears the strongest commitment to such realism out of all positions on offer.  Thus, Koons' thesis is extremely provocative as it targets one of naturalism's primary virtues.

Koons puts his thesis this way in his opening page:
"I will argue, somewhat paradoxically, that scientific realism can provide no support to philosophical naturalism.  In fact, the situation is precisely the reverse: naturalism and scientific realism are incompatible" (p.49).
He then fills out his thesis a bit more in his second page:
"I will argue that nature is comprehensible scientifically only if nature is not a causally closed system--only if nature is shaped by supernatural forces (forces beyond the scope of physical space and time)" (p.50, original italics).
Clearly, if it is true that nature requires influence from a supernatural force in order for science to produce knowledge, naturalism will be false.  If naturalists are unified on anything, they are unified by their mutual rejection of supernatural forces.  Thus, if Koons can make good on his claim, we have a decisive refutation of naturalism on our hands.

Now, what of his argument?  Koons needs two assertions to get his argument going.  First, he needs to establish what he calls "a preference for simplicity" in scientific practice:
"Philosophers and historians of science have long recognized that quasi-aesthetic considerations, such as simplicity, symmetry, and elegance, have played a pervasive and indispensable role in theory choice.  For instance, Copernicus's heliocentric model replaced the Ptolemaic system long before it had achieved a better fit with the data because of its far greater simplicity.  Similarly, Newton's and Einstien's theories of gravitation won early acceptance due to their extraordinary degree of symmetry and elegance" (p.50-1).
Second, Koons needs naturalism to require our knowledge-producing methods to, in a strict sense, reliably lead us to objective truths.  If, for example, our scientific methods lead us to the conclusion that X is true, there must be some kind of causal connection between X's objective properties and the scientific methods that detect X.  Namely, the properties of X must cause the scientific equipment to produce a certain reading that faithfully matches up with X itself.  What Koons wishes to eliminate here are "lucky guesses" or "mere coincidences."  Koons flushes this point with an analogy:
"By way of analogy, suppose I falsely believed that a certain coin was two-headed.  I therefore guess that all of the first six flips of the coin will turn out to be heads.  In fact, the coin is a fair one, and , by coincidence, the five of the first six flips did land heads.  Would we say in this case that my assumption was a reliable guide to the truth about these coin flips?  Should we say that its reliability was 5/6?  To the contrary, we should say that my assumption led to very unreliable predictions, and the degree of success that I achieved was due to good luck, and nothing more" (p.57).
Koons adds this on the next page:
"A method is reliable only when there is a causal mechanism that explains its reliability" (p.58).
With these two stipulations in place--the preference for simplicity in science and the requirement that our methods reliably track the truth--Koons' full argument can take shape:
1.  Scientific realism, plus the naturalistic commitment to reliable knowledge-producing methods, entails that scientific methods are reliable sources of truth about the world.

2. From the Principle of Simplicity, it follows that simplicity is a reliable indicator of the truth about natural laws.

3. Mere correlation between simplicity and the laws of nature is not good enough: reliability requires that there be some causal mechanism connecting simplicity and the actual laws of nature.

4. Since the laws of nature pervade space and time, any such causal mechanism must exist outside space and time.

5. Consequently, ontological naturalism is false. 1
Now, with a sketch of the main argument laid out, allow me to fill some of its major pieces out with some explanation.  First, I should explain that ontological naturalism is the proposition that no supernatural entities exist.  One way of stating the position is that it maintains that only natural entities exist.  Sometimes, but not always, naturalists cash out the idea of a "natural entity" in terms of "material" or "physical" entities.  Those distinctions are of no serious consequence to Koons' argument, though, because all naturalists are unified at least as far as supernatural entities (like God) are concerned: all naturalists reject the existence of supernatural entities.  So, if Koons successfully establishes that the commitments of scientific realism entail the existence of a supernatural entity, ontological naturalism is indeed false.

Second, I want to draw attention to the claim that the source of the simplicity relied upon by scientific theorizing is supernatural rather than natural.  Suppose that Koons and contemporary scientists are correct to prefer simpler theories to complex ones.  If that preference for simplicity is reliable--that is, it routinely produces true information about the world--then there must be some kind of explanation that grounds the reliability of that preference for simplicity.  As Koons points out, lucky guesses are not sufficient grounds for accounting for a method's reliability.  Instead, reliability depends on a kind of causal mechanism--something that forces scientific laws and principles to repeatedly wind up simple rather than complex.

What kind of force could perform such a task?  Koons' argument asserts, rightly in my view, that that force cannot be contained within the space-time universe.  This is so simply because the very laws and principles scientific theories are uncovering are the very laws and principles that govern the space-time universe.  In other words, simplicity is a property imposed upon scientific laws and principles, not a property generated by those laws and principles.  Put another way, simplicity is a principle all the laws of nature follow.  As such, then, it would be incoherent to assert that the mechanism that generates simplicity within the physical laws and structures of reality exists within the physical space-time world.  Thus, Koons seems to be right in asserting that such simplicity must originate from outside the physical space-time universe.  A mechanism operating from outside the physical world is, by definition, supernatural.

Supposing Koons' argument is successful for the moment, consider the awkward position this argument places the naturalist.  On the one hand, the naturalist wants to maintain an allegiance to the methods and findings of science, and this allegiance appears to require an embrace of the Principle of Simplicity.  On the other hand, the Principle of Simplicity, plus the strenuous demand for mechanism-like reliability present within empirical science, leads to a necessary supernatural mechanism to make simplicity a reliable guide to truth.  But naturalists, of course, define their position as the rejection of any kind of supernatural force or entity.  Koons' argument then gives naturalists the following option: either a) embrace naturalism but reject scientific realism, or b) reject naturalism but embrace scientific realism.

What maneuvers could a naturalist attempt to get out of this dilemma?  As best I can make out, there are only two plausible options.2

1. Embrace the Principle of Simplicity in scientific practice but deny that it requires a supernatural source.
2. Reject the Principle of Simplicity outright.

Koons addresses option (1) in his essay:
"[A naturalist] might try to salvage the reliability of a simplicity bias on the grounds that the laws of nature are, although uncaused, brute facts, necessarily what they are.  If they share, coincidentally, a form of simplicity and do so non-contingently, then a scientific method biased toward the appropriate form of simplicity will be, under the circumstances, a reliable guide to the truth" (p.58, original italics).
Koons provides two objections to this maneuver.  First, he says "there is no reason to suppose the laws of nature are necessary.  Cosmologists often explore the consequences of models of the universe in which the counterfactual laws hold" (p.58).  In order for a property of the world to be necessary, it must be impossible for any alternative world to exist without that property.  For example, it would be impossible for a world to exist where contradictions are possible.  E.g., it would be impossible to construct a world where an object is both a square and a circle, or a world where a star exists but doesn't exist at the same time.  So, the laws of logic are often considered metaphysically necessary in all possible worlds.  The laws of nature, by contrast, do not seem to carry the same sort of necessity.  Whatever constants and quantities the Big Bang event set in place for the laws of nature in this world, why should we expect that the constants and quantities we happen to observe had to be this way and no other?  In the absence of a sound account of why the laws of nature are necessary, maneuver (1) appears ad hoc or purely stipulative.

Second, maneuver (1) runs afoul of the naturalist's adherence to reliability.  In the absence of a causal mechanism, whatever properties the laws of nature happen to have are inexplicable.  The laws of nature just, somehow, "popped" into existence the way they are, and there's no reason why they are this way rather than another.  As far as reliability is concerned, there could not be anything reliable about detecting properties that inexplicably "pop" into existence uncaused.  What sort of method could one possibly use to reliably detect the existence of necessary, brute facts of reality that inexplicably appear?  Koons again has an analogy to round out his point:
"By way of illustration, suppose that we grant the necessity of the past: given the present moment, all the actual events of the past are necessary.  Next, suppose that a particular astrological method generates by chance the exact birthdate of the first President of the United States.  Since that date is now necessary, there is no possibility of the astrological method's failing to give the correct answer.  However, if there is no causal mechanism explaining the connection between the method's working and the particular facts involved in Washington's birth, then it would be Pickwickian to count the astrological method as reliable in investigating this particular event" (p.58, original italics).

Finally, option (2) above is to reject the Principle of Simplicity outright.  This option appears ad hoc in that a naturalist would not likely do this unless it were a last ditch effort.  As Koons documents in his book, the Principle of Simplicity has been a staple of scientific theorizing in modern history.  William of Occam's famous principle of parsimony, often dubbed "Occam's Razor," has long governed theory choice by stating, "all things equal, the simpler theory is to be preferred."  This strategy of denying the Principle of Simplicity, then, would put the naturalist once again at odds with the dictates of scientific realism.  One of the principle strategies in scientific investigations would be denied, and denied merely because it leads to a supernatural entity, not because it failed to aid good science.  Absent some independent account of why the Principle of Simplicity should be denied, this strategy would be excessivly ad hoc and therefore unsuccessful.

By my estimation, Koons' argument demonstrates that naturalism (which includes a demand for reliable mechanisms for explanation) and scientific realism (which includes the Principle of Simplicity) are incompatible.  Insofar as one wishes to embrace naturalism (i.e. reject supernatural forces), one must abandon scientific realism; insofar as one wishes to embrace scientific realism, one must abandon naturalism.  This is a surprising conclusion considering naturalists are often strongly wedded to scientific realism.  For those naturalists who grasp the gravity of this dilemma, it would be interesting to see where their commitments ultimately fall: Will they drop scientific realism to eliminate supernatural forces, or will they permit supernatural forces to preserve their commitment to realism?  I suppose there is a third option, which I suspect has been the most popular: just ignore the dilemma.

1. Argument adapted from pp. 55-56.  I omitted a few technical details from Koons' essay for the sake of brevity.
2. There may be others, but I suspect they would be weaker than the two I present.

No comments:

Post a Comment