Plantinga Propounds Invalid Argument

In his review of The God Delusion by Richard Dawkins, Alvin Plantinga, the John A. O'Brien Professor of Philosophy at the University of Notre Dame, admitted that he has propounded some invalid arguments in his life. It's good to know that he is aware of this fact but he seems to have done it again with his most recent argument.

His recent article in Christianity Today manages to misunderstand probability, biological evolution, Bayesian analysis and neurophysiology all at once in the service of his presuppositions. To start with, it's important to realize that although Plantinga is not himself a young-earth Creationist, he is sympathetic to them. He said in an earlier formulation of this argument:

Nonetheless a sensible person might be convinced, after careful and prayerful study of the Scriptures, that what the Lord teaches there (the book of Genesis -- ev) implies that this evidence is misleading and that as a matter of fact the earth really is very young. So far as I can see, there is nothing to rule this out as automatically pathological or irrational or irresponsible or stupid.

Plantinga himself believes that the earth is old because multiple lines of evidence converge to show this to be the case. Yet he is willing to accept the sensiblity of someone who does not accept the evidence that he does, because they are using their faith in scriptures and praying about it. If this is an adequate epistemology for a philosopher one wonders if there will be much in the rest of his philosophy to dream of or wonder about.

This credulity (that scripture and prayer are valid sources of knowledge for the Christian theist) is the crux of Plantinga's fallacy. He seems to accept the validity of Christian theism first and then adjudicate all positions in the light of this position in standard "presuppositionalist" ways. However these presuppositions simply don't conform with the evidence we have available. Of course, in Plantinga's mind, that is the fault of human minds. If our reason and the evidence lead us to doubt God, it is likely that our reason and evidence are wrong.

Specifically he says this:

I said naturalism is in philosophical hot water; this is true on several counts, but here I want to concentrate on just one—one connected with the thought that evolution supports or endorses or is in some way evidence for naturalism. As I see it, this is a whopping error: evolution and naturalism are not merely uneasy bedfellows; they are more like belligerent combatants. One can't rationally accept both evolution and naturalism; one can't rationally be an evolutionary naturalist. The problem, as several thinkers (C. S. Lewis, for example) have seen, is that naturalism, or evolutionary naturalism, seems to lead to a deep and pervasive skepticism. It leads to the conclusion that our cognitive or belief-producing faculties—memory, perception, logical insight, etc.—are unreliable and cannot be trusted to produce a preponderance of true beliefs over false. Darwin himself had worries along these lines: "With me," says Darwin, "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?"

Now I am certainly one to congratulate and reward someone who has a deep and pervasive skepticism. Skepticism is one of the very best tools to keep your wits, your money and your body safe. Yet skepticism is hardly a characteristic of naturalists alone. Christian theists are also skeptical, including Plantinga himself, who doubts that the Bible is correct on the age of the earth. One must wonder exactly what mechanism Plantinga imagines allows him to have the correct apprehension of this particular fact when so many of his "sensible" coreligionists and theists in general disagree with him on this point vehemently. Does he believe that his brain is working better than theirs? Yet this could not be for Plantinga, because he believes that brains don't detect true beliefs.

I know you think I'm kidding, but really, that is his position. He believes that brains by themselves are evolved organs and therefore can only be "adaptive" but that being adaptive does not entail the truth of a given conclusion arrived at by an adaptive organ.

Let's look again at his position about what he calls "neurophysiology":

Your beliefs may all be false, ridiculously false; if your behavior is adaptive, you will survive and reproduce. Consider a frog sitting on a lily pad. A fly passes by; the frog flicks out its tongue to capture it. Perhaps the neurophysiology that causes it to do so, also causes beliefs. As far as survival and reproduction is concerned, it won't matter at all what these beliefs are: if that adaptive neurophysiology causes true belief (e.g., those little black things are good to eat), fine. But if it causes false belief (e.g., if I catch the right one, I'll turn into a prince), that's fine too. Indeed, the neurophysiology in question might cause beliefs that have nothing to do with the creature's current circumstances (as in the case of our dreams); that's also fine, as long as the neurophysiology causes adaptive behavior. All that really matters, as far as survival and reproduction is concerned, is that the neurophysiology cause the right kind of behavior; whether it also causes true belief (rather than false belief) is irrelevant.

But this metaphor is absurd and wrong on the face of it. For a frog to catch a fly he first needs to adequately apprehend that there is a fly to be caught. This belief MUST be true for a frog to catch it. The frog's eye must accurately determine there is a fly in the field of vision. It must accurately gauge the speed and distance of the oncoming fly. It must accurately know the position of its tongue in its mouth and accurately direct its head and mouth at the correct angle to catch the fly. All of these things are things the frog's brain must believe first, before it can create an overarching belief that drives it to catch and eat the fly. Therefore Plantinga must admit that at least some of the beliefs the frog needs to have must correspond accurately to the external world. And of course, even in his example, the simplest belief is the one that is most correct, namely that the fly will feel better if it eats.

Plantinga's skepticism about neurophysiology assumes the accuracy of perception. Yet we all know that many perceptions themselves can be flawed. A few minutes with a magic-eyes book or even a glass of water and a pencil can show a child that. So if Plantinga's main point is that perception, memory, the brain's physics, working logic and apperception can be inherently flawed yet still adaptive, his point is one that neuroscientists have been making for several decades.

Yet Plantinga wants to take healthy skepticism and reduce it to a ridiculous solipsism that would be destructive to all knowledge. His way out is obvious:

Clearly this doubt arises for naturalists or atheists, but not for those who believe in God. That is because if God has created us in his image, then even if he fashioned us by some evolutionary means, he would presumably want us to resemble him in being able to know; but then most of what we believe might be true even if our minds have developed from those of the lower animals.

As a side point, the use of the term "lower animals" is simply another example of his lack of understanding of biology. A high-school level understanding of biology as it is taught in the 21st century would teach Plantinga that all life forms on earth are equally evolved. They have all derived from a common ancestor and have been adapting to changing environments and ecologies since then and all lineages extant have survived to this point. There are no "lower animals" unless you already accept creationism. But back to his main point.

According to Plantinga, while brains cannot evolve a method for detecting truth, God can give them that ability through his creation. Yet of course there is simply no logical connection between the existence of a theistic deity and the belief systems of organisms evolved under such a deity. I will give some alternatives that Plantinga fails to even consider, much less address, that show how limited his "supernaturalism" really is.

Example 1: There is a theistic deity. He does wish to make creatures in "his image" and intends to at some point in the future. We are "lower creatures" who can discern some of the deity's plans but remain ignorant about our role in them.

Example 2: There is a theistic deity who is evil and enjoys making a mockery of the creatures he watches evolving. They live and die with ridiculous beliefs about him and he chuckles about it like a pet owner chuckling at his dog when he puts peanut butter in his mouth.

Example 3: There is a deistic deity.

Example 4: The deity is panentheistic and is part of the entire process of creation and can only direct it from within matter, and thus is subject to the rules of matter.

Example 5: There are multiple supernatural beings who vie for control of the supernatural realm in a type of supernatural selection to propagate themselves and the supernatural substance they are created from.

There is simply no logical or philosophical reason to select Christian theism as the only rational alternative to methodological naturalism. Certainly there is no reason to assume the probability of one supernatural hypothesis over any other as there is simply no accepted supernatural data. Plantinga knows, however, that most of his readers are either Christian or former Christians and thus artificially limits his calculus to those two possibilities to make his outcome look superficially more plausible.

I specifically reject his use of Bayesian analysis in this article and the reason is the same one I give generically in all these situations. Bayes was discussing decisions made when there is a knowable a priori probability being discussed. The data that we have are then plugged in to that equation and an a posteriori calculation is then performed to determine the probabilities after the data is analyzed.

Yet our knowledge of universes is limited to an n of 1. Our universe, so far as we are able to talk with evidence about it, is sui generis. Therefore there cannot be a knowable a priori probability of a given type of universe existing from a pool of all possible universes. In fact, we can't even make a rational guess at how likely any given universe might be. This is like using a hammer to drive on the road. It's simply a ridiculous misuse of a tool.

When math is used improperly, it generates results that make no sense, and this is what happens when Plantinga uses it here. He is doing the equivalent of a sophomoric trick by dividing by zero unknowingly.

Even accepting his Bayesian analysis (which I do not) does not rescue his position however, because he is arguing that if most beliefs are false then all beliefs are false, which is unworthy of someone who has never taken a philosophy course, much less a professor. Certainly someone who has written three volumes on belief must know that there are techniques philosophers have devised over the centuries to separate true from false beliefs and that these techniques are far from universally employed -- even by philosophers, even by himself. While he does believe that he has had some true beliefs, he has admitted in his review of Dawkins that some of his arguments in the past have been invalid. How is it possible for his God-given truth detector to have allowed this?


After reviewing these facts and the gross misapprehension of how Bayes theorem works, it's fun to review another quote from his review of Dawkins:

You might say that some of his forays into philosophy are at best sophomoric, but that would be unfair to sophomores; the fact is (grade inflation aside), many of his arguments would receive a failing grade in a sophomore philosophy class. This, combined with the arrogant, smarter-than-thou tone of the book, can be annoying. I shall put irritation aside, however and do my best to take Dawkins' main argument seriously.

In that spirit, I shall put irritation aside, however and do my best to take the rest of Plantinga's argument seriously.

So Plantinga goes on to argue that if evolution is true than naturalism is disproved, because some of our perceptions are apparently true and adaptive. He believes that this can only be explained by the presupposition of theism:

Returning to methodological naturalism, if indeed natural science is essentially restricted in this way, if such a restriction is a part of the very essence of science, then what we need here, of course, is not natural science, but a broader inquiry that can include all that we know, including the truths that God has created life on earth and could have done it in many different ways. "Unnatural Science," "Creation Science," "Theistic Science"-call it what you will: what we need when we want to know how to think about the origin and development of contemporary life is what is most plausible from a Christian point of view. What we need is a scientific account of life that isn't restricted by that methodological naturalism.

Note that Plantinga simply asserts the "truth" that God has created life on earth. He gives no evidence for this position and also suggests that the entire scientific enterprise itself is somehow suspect because of his argument about methodological naturalism. Yet is this the case?

No.

Here's why not: Most beliefs are worthy of skepticism. The fact that most beliefs may be wrong is simply not an argument. Of course many or most beliefs may be wrong. It is the job of philosophers to counteract wrong arguments and beliefs by coming up with ways to avoid them. Yet if we assume, as Plantinga does, that the only way we can have correct beliefs is because God is letting us have them, there is simply no job left for the philosopher. He may abdicate his job and let the workings of the deity do its business.

Yet of course, Plantinga must be aware of the proliferation of false beliefs on this earth and their ubiquity. In a day's conversation he must encounter multiple false beliefs. Yet he gives no explanation about how a God-given method for detecting truth would operate. He has certainly never demonstrated a technique that differs from that of methodological naturalism. Is there a way to show that true beliefs can only exist for those whom God is blessing with them?

Given the nearly universal presence of false beliefs, this is a strong acid that Plantinga is playing with, and from my point of view it dissolves the bottle that he is trying to carry it in.

To wit, if we accept his proposition, arguendo, that organisms that have evolved in a natural world may very well evolve to have adaptive but false beliefs that are widespread, does that not comport pretty well with the world we see? In fact, assuming naturalism, would we not expect to see hierarchies of beliefs that coexist and a mixture of some falsehood and some truth within those hierarchies of belief?

In fact what we see is nearly universal acceptance of directly perceived facts. Only the craziest among us will doubt there is a yellow lemon in the room when we are all staring at one. This is a directly perceived object which fits neatly in a perceptual category for which we have a concrete word. The same goes for our beliefs when driving a car. There is little room for skepticism about an oncoming car and false beliefs about such a thing will rapidly result in negative consequences for the individual that has them.

Our brains and perceptual systems of course are not evolved to create true beliefs, Plantinga is certainly correct about that, but they are evolved to create accurate perceptions. And each perception that we have insinuates itself into a rounded and whole set of beliefs, each of which is reinforced by the other.

However some beliefs have very few perceptions on which to base themselves on. For example, a sense of awe at seeing something greater than oneself is quite remarkable when it happens, but differing things awe different people. One person is awed by the Taj Mahal, another by Yosemite, and another by the starry sky at night. There simply is no general agreement on awe. And thus, when people discuss awe, there is more nuance, less agreement, and more difficulty at achieving a consensus of truth.

Even moreso when we get to beliefs based on no direct perceptions at all: Mohammed rode a winged horse to Jerusalem. The Buddha forewent nirvana to become a bodhisattva. The Great Spirit will protect the plains and their bison. Quetzalcoatl has appeared in Veracruz and is on his way to Tenochtitlan to usher in the next age.

The Christian theist must -- if he accepts Christianity as true, be skeptical about all these strongly held beliefs. Yet by what mechanism then does he trust his own beliefs about his own religion? According to Plantinga, God allows him to see the truth of them. Yet is it not possible, yea, even probable that God is allowing someone else to see a truth and not allowing the Christian?

Plantinga simply fails to address this possibility.

His argument seems to fail in two directions then. In one direction it simply asserts a truism of philosophy that has been known since the presocratics, namely that some perceptions and some beliefs that are accepted as accurate by those who hold them are wrong. The proper response to this as far as I can tell is, "Duh."

The second way it fails though is the much more spectacular, for by expressing contempt for methodological naturalism, it eviscerates all but the most uncritical, fundamentalist theism, something Plantinga himself seems to think is "sensible" but that he does not yet wish to fully endorse.

His lack of a method for God's image to function as a truth-maker leaves his corrosive skepticism for naturalism eating away at the vessel he carries it in until they both lie on the ground at his feet, bubbling, oozing and evaporating away into the air.