An Evolutionary Argument Against Theism

Despite the long history of debates between theists and atheists, it is truly impressive how modern philosophers have continued to innovate how we think about the question of whether God exists. The establishment and mainstream acceptance of the theory of biological evolution by natural selection—given its first thorough articulations by Charles Darwin and Alfred Russel Wallace in the 19th century—has had a massive impact on theological inquiry, and on philosophy more broadly. In this post, I will respond to a modern attempt by an esteemed theist philosopher to use evolutionary theory against naturalism, concluding that this attempt ultimately fails. I will then build my own argument against theism, showing that evolutionary theory presents a serious philosophical problem for theists.

Is Evolution Compatible with Naturalism?

The Christian philosopher Alvin Plantinga proposed a philosophical argument against naturalism known as the evolutionary argument against naturalism (EAAN), in which he argues that one cannot reasonably hold that both naturalism (i.e., the belief that there is no God or supernatural reality) and biological evolution are simultaneously true. Plantinga first establishes that on a naturalistic worldview, your cognitive faculties are only the result of physical processes in your brain which have evolved for some adaptive advantage via natural selection. The neurological processes that are adapted for advantageous behaviors are also responsible for our beliefs, but there is no necessary reason for our beliefs to be true. You can watch the video below to hear Plantinga make this argument in his own words (you can also read Plantinga’s 1994 paper, Naturalism Defeated, where he outlines this argument in greater detail):

Video posted to YouTube by Templeton Prize

It certainly seems to be the case that our beliefs would have some degree of truth, given that the neurology that produced the beliefs is also responsible for advantageous behaviors which adapt us to the real world. However, Plantinga doesn’t find this objection to be convincing and insists that despite the seeming truth of our perceptions, evolution cannot give us confidence that our beliefs are true in a naturalistic worldview. Notice, for example, toward the end of the video above at around the 11-minute mark, Plantinga responds to the argument that evolution might be likely to produce true beliefs by quipping that “you can’t give some kind of argument for your cognitive faculties being reliable because… the argument is going to have premises, and if you’re relying on these premises you’re trusting your cognitive faculties, you’re taking for granted that they’re reliable.”

Of course, Plantinga is correct that any argument presupposes trusting our cognitive faculties, but this is just as true for theistic arguments as it is for naturalistic or atheistic ones. The theist cannot make a theistic argument for trusting in their cognitive faculties without already presupposing the reliability of their cognitive faculties to build a logical argument in the first place. It’s a double standard that Plantinga accepts theistic arguments along with all of their epistemological assumptions but rejects naturalistic arguments on account of the fact that they require some epistemological presuppositions. This problem was noted by Branden Fitelson and Elliot Sober in their critique of Plantinga’s EAAN:

“Plantinga suggests that evolutionary naturalism is self-defeating, but that traditional theism is not. However, what is true is that neither position has an answer to hyperbolic doubt. Evolutionists have no way to justify the theory they believe other than by critically assessing the evidence that has been amassed and employing rules of inference that seem on reflection to be sound. If someone challenges all the observations and rules of inference that are used in science and in everyday life, demanding that they be justified from the ground up, the challenge cannot be met. A similar problem arises for theists who think that their confidence in the reliability of their own reasoning powers is shored up by the fact that the human mind was designed by a God who is no deceiver. The theist, like the evolutionary naturalist, is unable to construct a non-question-begging argument that refutes global skepticism.”

(Fitelson and Sober, 13)

An Evolutionary Argument Against Theism

Having spent a considerable amount of time reading and thinking about the philosophy of religion, I have developed what I consider to be a fairly persuasive evolutionary argument against theism (EAAT). The argument partly relies on an argument that was developed by the philosopher Quentin Smith, which Smith refers to as an atheological argument from evil natural laws. Smith summarizes his argument in the following way:

(1) God is omnipotent, omniscient, and omnibenevolent.

(2) If God exists, then there exists no instances of an ultimately evil natural law.

(3) It is probable that the law of predation is ultimately evil.

(4) It is probable that there exist instances of the law of predation.

Therefore, it is probable that

(5) God does not exist.

Smith’s argument is a variation of the philosophical problem of evil. There are two basic versions of the problem of evil: the logical problem of evil and the evidential problem of evil. The logical problem argues that there is a logical contradiction between the existence of God and the existence of evil, and therefore since most people believe that evil exists, it is logically necessary to conclude that God does not exist. The evidential problem accepts that it is logically possible for both God and evil to exist simultaneously, however, it proceeds to argue probabilistically that evil makes the existence of God unlikely. Smith’s argument from evil natural laws seems to be of the evidential variety, arguing that evil natural laws make it probable that God does not exist without denying that it is still logically possible for God to exist.

Alvin Plantinga has done significant work on the problem of evil, especially in developing the free will defense which I discussed in a previous post. Plantinga’s free will defense basically argues that if libertarian free will is possible, then it is possible that by giving humans free will God had no choice but to allow evil despite being all-powerful and all-loving. At first glance, this defense appears useless for refuting Smith’s argument because the law of predation applies to animals rather than humans, so free will might not be at play. However, Plantinga has attempted to employ the free will defense to solve the problem of natural evil as well, by arguing that natural evils are potentially caused by non-human free will agents:

“What about natural evil? Evil that can’t be ascribed to the free actions of human beings? Suffering due to earthquakes, disease, and the like?… a more traditional line of thought is indicated by St. Augustine (p. 26), who attributes much of the evil we find to Satan or to Satan and his cohorts. Satan, so the traditional doctrine goes, is a mighty nonhuman spirit who, along with many other angels, was created long before God created man. Unlike most of his colleagues, Satan rebelled against God and has since been wreaking whatever havoc he can. The result is natural evil. So the natural evil we find is due to free actions of nonhuman spirits.”

(Plantinga, 1974: 57-58)

It should be pointed out that Plantinga’s free will defense is primarily aimed at the logical problem of evil, which as I’ve already mentioned is not the variety of argument that Smith is using. Plantinga is arguing only that a free will explanation is possible, whereas Smith is not concerned with possibility but rather probability. It is therefore easy for Smith to dismiss Plantinga’s proposed solution as an unlikely possibility, and therefore not damaging to Smith’s argument (see Smith, 171-172).

A Logical Contradiction Between Evolution and Theism

While Smith has developed an evidential/probabilistic argument from natural evil, his argument has inspired me to consider the possibility of a logical argument from natural evil. I tend to prefer logical arguments over evidential arguments, and I believe there is a logical argument that undercuts Plantinga’s free defense against natural evil that is just as (if not more) persuasive than Smith’s. I submit that all we need to do is add evolutionary biology into the mix, and we can easily construct a logical argument that completely circumvents Plantinga’s defense. As with all logical arguments, I do not assert that my conclusion is necessarily true, but rather that if all of my premises are true then my conclusion necessarily follows from the premises.

The logical problem of evil, which Plantinga’s defense is responding to, asserts that there is a logical contradiction between the existence of evil and a God who is both all-loving and all-powerful. If God is all-loving, he could prevent all evil, and if God is all-powerful, he would be able to prevent all evil. Therefore, if God existed, he would not have allowed the evil that we see in the world, and therefore we can conclude that God does not exist.

Plantinga’s free will defense argues that it is not necessarily true that an all-powerful God can prevent all evil. Being all-powerful does not grant God the ability to do things that are not logically possible, such as make a married bachelor or a round square. Likewise, if it is possible that libertarian free will is true, then it is also possible that God could not create beings that freely choose to never do evil things, for it is logically impossible for God makes people avoid doing evil since free will requires the possibility to choose evil actions. (In my previous blog post, I argue that libertarian free will is itself a logical impossibility, and therefore fails as a defense against the problem of evil, but for the sake of argument I will grant the possibility of libertarian free will in this post).

As we saw above, Plantinga argues that it is possible (even if not probable) that evil spirits, such as Satan, are responsible for the evils we see in the natural world, and this defense is certainly possible in theory. However, when extended to the problem of evil natural laws–such as the law of predation–the issue gets more complicated than Plantinga (or even Smith) appears to appreciate. I would argue that Plantinga holds two beliefs that together invalidate the free will defense as applied to natural evil: evolution and theism.

Theists tend to believe that God is the creator of all the earth’s biological organisms and that God has specially designed each creature with great wisdom. In the book of Genesis, the first book of the Jewish and Christian Bibles, we read that God created all living creatures, including humans (Genesis 1:20-28). The theistic position, I would argue, is therefore that God is ultimately responsible for the incredible complexity of earth’s biosphere.

However, like many educated theists, Plantinga appears to accept (or at least be open to) the idea that evolution by natural selection is a true proposition. The idea that evolution by means of natural selection was the method by which God created earth’s biodiversity, including humanity, is now fairly mainstream—in a 2013 poll, 24% of American adults agreed that “a supreme being guided the evolution of living things for the purpose of creating humans and other life in the form it exists today.”

Here is where the contradiction comes into play: in order for God to have created every living thing exactly the way it is today via natural selection, he would have needed to determine every step of the process (perhaps by setting up the preconditions just so) in order to get the kinds of organisms that exist. The problem with this is that the law of predation, this evil natural law as identified by Smith, is an essential part of our design. If predation was not so massively prevalent across the animal kingdom, there is simply no way that natural selection would have sculpted humans and other animals to look, think, and behave the way they do today. This is a problem because it means that in order for God to have intentionally created the animal kingdom like it is today, then he must be responsible for using predation to get there. If you attribute the law of predation to free will beings other than God, then God can no longer be responsible for the specific attributes of living creatures (at the very least, God can only be said to be responsible for the possibility of these specific attributes, but not for their actualization). So if true libertarian free will was involved in the way that Plantinga describes, then it is largely the free choices of malevolent spirits that sculpted human beings. We have a catch-22: either 1) God created us, and is therefore responsible for evil natural laws, or 2) God is not responsible for evil natural laws, but we were created by demons.

Plantinga’s free will defense is weakened by the reality of evolution by natural selection (which includes the evil natural law of predation). Other philosophers have put forward theodicies and defenses against the problem of natural evil that do not appeal to free will, and so this logical contradiction is specifically aimed at Plantinga’s particular way of dealing with natural evil. I find this logical argument from evolutionary natural evil–an evolutionary argument against theism–to be more forceful than probabilistic arguments, such as Smith’s, and hopefully a useful employment of evolutionary theory to the question of whether a theistic God exists.


Fitelson, Branden, and Sober, Elliot. “Plantinga’s Probability Arguments Against Evolutionary Naturalism.” University of Wisconsin–Madison (1997).

Plantinga, Alvin. “Naturalism Defeated.” (1994).

Plantinga, Alvin. God, Freedom, and Evil (Eerdmans, 1974).

“Public’s Views on Human Evolution.” Pew Research Center (2013).

Smith, Quentin. “An Atheological Argument from Evil Natural Laws.” International Journal for Philosophy of Religion 29 (1991): 159-174.

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