Aquinas & Intelligent Design

Thomistic evolutionists maintain that Aquinas’s philosophy/theology is incompatible with the modern theory of intelligent design (ID). At the same time they say it can be reconciled with neo-Darwinism. This may seem odd even for a non-Christian. There may be different reasons why Thomistic evolutionists chose to counter ID: Some may be ignorant of it, some may fear “the scientific community” and “the scientific consensus.” Still others may actually believe that arguments for ID somehow threaten the old Thomistic arguments for God’s existence known as the Five Ways. However, Thomistic evolutionists have never worked out any consistent opinion on intelligent design. They employ many different arguments, even mutually contradictory ones, which they borrow from either the atheistic evolutionary arsenal or the theistic one, or even from the “young earthers.” Thus we hear that ID is reductive, that it excludes Aquinas’ Fifth Way, that it affirms a “god of the gaps,” that it is not scientific, that it is non-Christian, or that it is mechanistic. A thorough response to no less than sixteen arguments gathered from Thomistic anti-ID literature is to be found in the book Aquinas and Evolution. Here we will present just three of them along with the responses (see below). But first we need to explain what ID is.

What Is Intelligent Design?

The best place to find a correct definition of intelligent design is on the website created by the authors of this theory. Most of the critique filed against ID is based on “straw man” fallacies because it operates on an incorrect understanding of ID. Also, many Thomists accept a caricature of this theory propagated by popular media. Therefore, the first step in answering much of the criticism of ID is simply to obtain a correct understanding of ID. At we read:

Intelligent design refers to a scientific research program as well as a community of scientists, philosophers and other scholars who seek evidence of design in nature. The theory of intelligent design holds that certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection. Through the study and analysis of a system’s components, a design theorist is able to determine whether various natural structures are the product of chance, natural law, intelligent design, or some combination thereof. Such research is conducted by observing the types of information produced when intelligent agents act. Scientists then seek to find objects which have those same types of informational properties which we commonly know come from intelligence. Intelligent design has applied these scientific methods to detect design in irreducibly complex biological structures, the complex and specified information content in DNA, the life-sustaining physical architecture of the universe, and the geologically rapid origin of biological diversity in the fossil record during the Cambrian explosion approximately 530 million years ago.

Argument 1

Some Thomists believe that the theory of intelligent design is reductive in the sense that it diminishes the philosophical quest for God and replaces it with the arguments which actually never reach God. By this, intelligent design is one of the “reductionisms” pervading contemporary science, similar to mechanicism, naturalism, materialism, etc.


This argument is inspired by an incorrect classification of ID within philosophy rather than natural science. Thomists who employ this argument commit a twofold mistake: On the one hand they require from ID that it be “good philosophy” which in fact is not the goal of this theory, and on the other hand they deny it the status of “true science” because, according to them, it goes beyond the scientific method and enters the field of philosophy. Both charges stem from the rejection of intelligent design as science. But if we read the definition above we cannot come to the conclusion that ID pretends to be a philosophy.

Further, some Thomists deny the very distinction between natural science and philosophy. This misunderstanding stems from an automatic extrapolation of an outdated, pre-modern division of disciplines to our era. It may be true that in ancient and medieval times sciences were just a part of philosophy, let’s say, philosophy of nature. But  natural sciences have grown enormously since modernity and gained their own independent methods and goals. It does not follow that natural science and philosophy are isolated or contradictory. The relation between modern science and philosophy is analogous to the relation between philosophy and theology. There are strictly theological doctrines which are different from (but not contradictory to) the strictly philosophical claims. For example, the theological doctrine of the Holy Trinity is different from the philosophical concept of an Absolute who is the first cause of everything. Similarly, there are strictly scientific theories which are independent from any philosophical claims, even if they are compatible with some of them and incompatible with other. For example, the scientific theory of the “Big Bang” is different from, but not contradictory, to the theological doctrine of creatio ex nihilo (creation out of nothing).

Similarly, the scientific argument for design from “irreducible complexity” is different from a philosophical argument for the existence of God such as the Fifth Way, but is not contradictory to it; “irreducible complexity” proves design within the domain of science whereas the Fifth Way demonstrates the existence of God within the domain of philosophy. Once we accept the distinction between philosophy and science there is no problem of reductionism in intelligent design. This theory cannot obtain the same effects as philosophy, because it is not her goal. For example, intelligent design knows nothing about formal cause, which is a proper domain of metaphysics. However, it does not follow that ID denies the existence of formal causes. It is simply beyond the goal of science to find this kind of cause and since ID is scientific it is not concerned with formal causes. Reductionism would take place if a scientist said that ID is all that it takes to ultimately explain reality. But ID does not say that. ID supporters are actually more open to philosophy and theology than their scientific opponents from the neo-Darwinian camp. In fact, there are neo-Darwinists who claim that  Darwinian-like theories provide an ultimate explanation of biological origins. Consequently it is neo-Darwinism rather than ID which falls under Thomistic accusation of being reductive.

Argument 2

Some Thomists believe that ID proponents, by using examples of mechanisms created by men to explain biological design, reduce living beings to mechanisms. Thomists, in contrast, affirm that living beings are not mechanisms. Living beings have an immaterial principle of their operation which is the form (the soul). Living beings transcend matter and cannot be reduced to a set of chemical relations or conglomerates of parts. Therefore, the method used by intelligent design contradicts Thomistic philosophy.


This argument confuses an analogy with an identification. Science rarely speaks about an organism as a living whole. Especially when it comes to the argument from irreducible complexity, intelligent design operates on parts of organisms which clearly act as parts in mechanisms, such as human-made engines. The analogy between the bacterial flagellum and the boat engine is obvious. Some Thomists deny the very possibility of making an analogy between artifacts and natural things, but they fall in conflict with Thomas Aquinas who explicitly validates it. Aquinas writes:

[I]n all things moved by reason, the order of reason which moves them is evident, although the things themselves are without reason: for an arrow through the motion of the archer goes straight towards the target, as though it were endowed with reason to direct its course. The same may be seen in the movements of clocks and all engines put together by the art of man. Now as artificial things are in comparison to human art, so are all natural things in comparison to the Divine art. And accordingly order is to be seen in things moved by nature, just as in things moved by reason. (S.Th. I-II,13,2 ad3).

All creatures are compared to God as artificial things (artificiata) to an artificer… Whence, the whole of nature is like an artifact (artificiatum) of divine art. (ScG III, 100, 6).

Natural things depend on the divine intellect, as artificial things depend on the human intellect. (S.Th. I, 17, 1, co).

Art imitates nature. The reason for it is that principles relate to each other in the same way as the operations and the effect relate proportionally to each other. The principle of the things happening by art is the human intellect, which is derived from the divine intellect according to some similarity. And the divine intellect is the principle of natural things. Hence, it is necessary that the operations of art imitate the operations of nature. And those things that are produced by art imitate those found in nature. (Sent. Politic. pr. 1).

Argument 3

Some Thomistic evolutionists bring up a popular argument against ID called “god of the gaps.” According to the “god of the gaps” objection, we cannot assume divine causality when a natural cause is unknown, because once the natural cause becomes known divine causality disappears. This would be like filling the gaps of our knowledge with an unknown supernatural power. Scientific progress removes that power, creating an impression that religion provides just provisional explanations. Intelligent design falls under the “god of the gaps” charge because it postulates divine causality to explain the gaps in the Darwinian explanations of the evolutionary processes.


There are at least two problems with this argument. First, the argument of “god of the gaps” does not apply to intelligent design. Second, it fails as an argument altogether due to its deficient logic.

Regarding the first problem we need to observe that there is no indication in the definition above that intelligent design resorts to a divine or supernatural causality in the universe. Since a god is not a part of the theory there cannot be the “god of the gaps” fallacy in it. Neither is it true that intelligent design postulates intelligent causality just because of ignorance. On the contrary, irreducible complexity can be inferred only after all of the parts of a given biological structure have been discovered and their function has been understood. It is positive knowledge about a given biological structure rather than ignorance which allows scientists to adjudicate whether that structure is irreducibly complex or not, and whether it could be produced by chance or not.

The second problem is that according to the logic of the argument it would never be allowed to assume divine causality, because theoretically every effect in the universe may have a natural explanation. For example, the Resurrection of Christ required direct divine action, which is not a natural explanation. But the Pharisees claimed that the body of Christ was stolen from the grave, whereas liberal exegetes say that the Resurrection described in the Gospels is just a projection of the desires of the community who wished that Jesus’ mission was successful. So there are at least two natural explanations of the Resurrection. Consequently, if one postulates direct divine causality in the Resurrection, one inserts God into the gaps of our knowledge. Those “gaps” might later be removed by biblical scholars.

The same applies to any other miracle. For example, if we don’t know how the bread was multiplied, we should say that it is just a matter of time until science will be able to explain it; by postulating divine supernatural causality in the multiplication of the loaves, a theologian would fall into the error of “god of the gaps.” According to the logic of this argument, one should always assume that there is a material and natural explanation to any physical event. Only then can the “god of the gaps” fallacy be avoided. Yet, according to Christianity, some physical events do not have a physical explanation. A Christian is obliged by faith to accept that there are “gaps” in human knowledge about the material universe. In those cases God is not “inserted” into the gaps; rather, God is the only and true explanation. The charge of “god of the gaps” does not allow such thing, even provisionally. Thus, the charge is consistent with naturalism, but not with Christianity.  It is therefore not consistent with an authentic Thomist perspective.

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