I don’t plan on commenting on every book I read but I was compelled to address what appeared to me to be some glaring omissions and one audacious claim in the argumentation found in Alvin Plantinga’s “Where the Conflict Really Lies: Science, Religion, & Naturalism”. There were three particular assertions that caught my attention: (1) that evolutionary theory says nothing about whether it is unguided, (2) a logical proof that determinism is false, and (3) that unguided evolution cannot yield reliable beliefs (aka “the evolutionary argument against naturalism”, or EAAN).

There is no reason to believe that evolution is unguided?

Ignoring the theological implications and biblical creation accounts, Plantinga says that “The scientific theory of evolution as such is not incompatible with Christian belief; what is incompatible with it is the idea that evolution, natural selection, is unguided.” I agree that it is not necessary to assert that evolution is unguided. There is no way that we can show that some supernatural agent is not overseeing the genetic changes which drive evolution. Fair enough. However, Plantinga goes on to say that “But that [the idea that evolution is unguided] isn’t part of evolutionary theory as such; it’s instead a metaphysical or theological addition.” What struck me is that Plantinga seemingly makes this claim without engaging with the foundational reasons why evolution is generally defined to be unguided. Instead, he chooses to review the arguments which show how complexity could arise by an unguided process. Yes, those arguments don’t prove that the process is unguided but that is beside the point. The task at hand is to find the best explanation for our observations. Is the best explanation that evolution is guided, or is the best explanation that evolution is unguided? When I survey the data, I see compelling reasons for inferring an unguided process. For example:

1. The vast majority of species that have ever existed are now extinct. Natural selection occurs by killing off creatures with the less favorable property. Competition and death are fundamental components of the evolutionary process.
2. It is far more likely that a mutation is neutral or deleterious than beneficial.
3. What were once beneficial adaptations can become deleterious in the face of a changing environment.
4. Artificial selection (for example, in dogs) has produced in hundreds of generations a degree of variation that is only comparatively realized in nature over thousands of generations.

Among others, these are all characteristics of evolution which, to me, infer an unguided process. The first observation demonstrates how wasteful, vicious and “immoral” the process is. If you want to argue that we have no reason to believe that God wouldn’t create through such mechanisms then that’s fine, but at least admit that it is not how we expect an all-loving, all-powerful, super-intelligent being to act and is among the least attractive of the possible methods (e.g., special creation). The second observation highlights how the process seems to be driven by a small fraction of changes in a probabilistic paradigm, which is almost by definition the opposite of a guided process. The third observation demonstrates that the result of selection does not always lead to a long-term benefit. Again, this seems to contradict an intelligence behind the outcomes. Lastly, the final observation reveals how inefficiently slow the changes are accumulated in nature, whereas a known intelligent agent (humans) has succeeded in utilizing the exact same underlying mechanisms to realize dramatic changes in a short period of time.

On the flip side, one could argue that the amazing outcomes of evolution – the eye, flight, the brain – are all pointers toward a guiding intelligence. I understand this view; it is truly amazing what has been wrought. I feel the draw of the design explanation when I consider the remarkable intricacies of life, but I also recognize that this pull arises because the design hypothesis is easier to relate to our experience (i.e., our intuitions are biased toward that model). This is not the place to rely on intuitions, however, so we must turn to the evidence. In a twist of irony, Plantinga has already included arguments which explain how these wonders may result from an unguided process. So the counter to the argument for guided evolution has been presented and acknowledged. As I see it, this means that the reasons for thinking that evolution is unguided weren’t addressed at all and the reasons for thinking that evolution is guided were found to also fit the unguided paradigm. I cannot agree that this conflict is merely superficial.

Determinism is logically impossible?

Though it is a minor side-note in the book, it immediately caught my attention. What an audacious claim – a logical proof that determinism is false! This warranted a closer look. The argument is as follows:

1. A natural law is of the form “If the universe (U) is causally closed, then P.”
2. Also take the conjunction of all natural laws to be “If U is causally closed, then P.”
3. If determinism is true then the conjunction of all natural laws (If U is causally closed, then P) and a specific past state of the universe (PAST) necessarily entails the future (F).
4. Using N to mean Necessarily, the above statement is equivalent to: N [if (if U is causally closed then P) and PAST, then F].
5. Becomes:  N [if (either U is not causally closed or P) and PAST, then F]
6. Becomes:  N [if [(PAST and P) or (PAST and U is not causally closed)], then F].
7. This takes the form N if (p or q) then r, which means that both p and q entail r, hence
8. N [if (Past and P) then F] and N [if (PAST and U is not causally closed) then F].
9. The right hand side of #8 is obviously false because there is clearly a possible world that (i) shares its past with the actual world, (ii) is not causally closed (because perhaps God acted) and (iii) does not share its future with the actual world. Therefore, determinism is false.

I will admit that it took me several reads to follow this argument. In the end, however, I think I see the slight of hand (whether or not this was intentional, I do not know). It was my attempt to translate this into software code that clearly revealed the problem for me. Here’s the code:

function CreateFuture(Universe, Past) {
  if(Universe.CausallyClosed) {
    P = Universe.NaturalLaws;
  }
  return DoPhysics(P, Past);
}

My fellow software engineers will immediately recognize the bug in this function: if the universe is not causally closed then P is undefined and an attempt to use it to generate the future yields unpredictable results. This is the key to the problem with the proof. In step 5, Plantinga expands the proof to cover both branches of the conditional and infers that both branches are still bound within the definition of determinism. This then, of course, leads to the obvious result where the future created with defined natural laws may be different than the future created with undefined natural laws. Plantinga groups these outcomes together under the definition of determinism and declares that the internal inconsistency shows that determinism is false. This is completely invalid, however, because determinism is only defined to be the branch where the universe is causally closed. All other branches (or possible worlds) are something other than determinism. I am honestly a bit baffled that Plantinga chose to include this in the book.

Despite my rejection of this proof, I should note that I am not a strict determinist. I would consider myself something of a quasi-determinist. Quantum indeterminacy has shown us that we can’t (yet) predict all possible states, but the quantum effects adhere to a predictable distribution such that the macro-world, and even the molecular world, behaves according to the physical laws to the extent that we have accurately described them. In the absence of supernatural intervention the natural world is, for all practical purposes, deterministic.

Naturalism cannot yield reliable beliefs?

The central thesis of the evolutionary argument against naturalism (EAAN) is that, without a guiding force, there is no reason to believe that the evolutionary process would result in a belief forming system that yields true beliefs. As I read through the EAAN, I was eagerly anticipating Plantinga’s response to the following objection: evolutionary theory claims that well before any creature was conscious there were sensory systems that triggered responses which selected the population. Selection is dependent on beneficial interactions with the external world. If those interactions do not consistently and properly map to the outside world then they are less likely to be beneficial. Consciousness and belief formation are extensions of this rudimentary system. As such, the evolutionary processes which led to sensory response systems, and therefore also to consciousness and belief formation, are likely to produce reliable reflections of the outside world.

Finally, in chapter 10, part 5, section C he gets there. He introduces the objection with “Isn’t it just obvious that true beliefs will facilitate adaptive action?” and eventually follows-up with “Yes, certainly. This is indeed true. But it is also irrelevant.” Then comes the explanation: “We ordinarily think true belief leads to successful action because we also think that the beliefs cause actions, and do so by virtue of their content… But now suppose materialism were true: then, as we’ve seen, my belief will be a neural structure that has both NP [neuro-physiological] properties and also a propositional content. It is by virtue of the NP properties, however, not the content, that the belief causes what it does cause.” After providing several examples of how the content of beliefs result in action, he finishes with “Going back to materialism…If the belief had had the same NP properties but different content, it would have had the same effect on behavior.”

Plantinga immediately recognizes that materialism would deny that it is possible for two beliefs to have the same NP properties but different content. Then things get messy. He digresses into a brief discussion of how this isn’t the place to address how counterfactuals and counterpossibles should be used in argumentation. Then he closes the response with “..it doesn’t matter to the adaptiveness of the behavior (or of the neurology that causes that behavior) whether the content determined by that neurology is true.” Wait a second – isn’t that where we were before this whole objection was raised?

Is it just me, or did he completely misrepresent the naturalistic ontology of belief and then dismiss the objection to that misrepresentation without offering an explanation? It seems as if he has superimposed dualism onto naturalism and then argued against this bastard child. What really confuses me is that in the pages leading up to this he clearly defined the materialistic view as one in which belief content can be reduced to NP properties. Somehow, when it came time to address the big objection, this reduction no longer applied and content was now something completely separate from the physical. How did this happen? I re-read those pages several times and I just don’t get it. Am I in over my head? Did I miss something? I can’t help but feel like I did; but, then again, I’m far from being the only one who has seen problems with this argument. This turn of events left me bewildered and I can’t give any regard to the EAAN until this is resolved.

Closing Thoughts

This was my first encounter with any of Plantinga’s books, though I was familiar with his work and was well aware of his reputation as one of Christianity’s greatest thinkers. The writing generally lived up to the standard; the text was lucid and, in most cases, the arguments were easy to follow. It was a worthwhile read. In the end, however, I was severely disappointed that his key claims – the “apparent conflict” between theism and evolution and the “deep conflict” between naturalism and science – ultimately omit or dismiss the most relevant objections to those claims. Perhaps even more alarming was that he chose to publish a clearly flawed proof that determinism is false. Collectively these observations have done nothing but tarnish his reputation in my eyes. I had hoped for something more.