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A Few Thoughts on the Cronin-Tour Debate

Photo: Lee Cronin, via YouTube (screenshot).

Recently, the Cambridge Faculty Roundtable hosted a very interesting debate at Harvard (see below) about science and the origin of life. The main participants were chemistry professors Dr. James Tour and Dr. Lee Cronin. Tour is an organic chemist at Rice University and an outspoken critic of the current state of origin-of-life research, while Cronin is a British chemist and a prominent researcher in the field of chemical self-organization and abiogenesis. Cronin wants to reverse-engineer life from the bottom up and create artificial life, rather than explain the historically contingent event of the actual origin of the first living cell. 

Unlike James Tour’s earlier debate with YouTuber Dave Farina, this event was a very civil and respectful interaction between two distinguished scientists, who both have interesting and important things to say. Therefore, I want to use this opportunity to offer some personal thoughts. Since biochemistry, molecular biology, and information theory are outside my field of expertise, I will restrict my commentary to a more general issue that I found quite revealing. It is very much relevant to the status of intelligent design theory.

“False Claims by Cronin and His Group” 

In the debate, Tour insisted on precise chemistry, while Cronin elaborated on vague ideas of Assembly Theory and selection doing its thing. Cronin proposed Assembly Theory in 2017. But it was only the recent publication on the subject in the prestigious journal Nature (Sharma et al. 2023) that made a real splash, generating headlines around the world. Tour quite correctly pointed out that Assembly Theory does not bring us a single step closer to understanding how a first cell, a first replicator, or even just the main building blocks of life could form under the conditions of the early Earth. Tour’s critique is echoed by other scientists including Dr. Hector Zenil at Oxford University. As Zenil wrote in an update to his article for Medium, “The 8 Fallacies of Assembly Theory”:

While I may not share all of Prof. Tour’s set of beliefs regarding religion (he did not use any religious arguments to refute Cronin’s claims), I think he did a service to science and scientific practice by pointing out the many false claims by Cronin and his group.

A Precise Level of Complexity 

Nevertheless, Assembly Theory has some interesting aspects. The most intriguing is that it provides an objective measure of the complexity of parts that arguably allows for a reliable empirical detection of life and its products, distinguishing it from any results of abiotic processes. This has important implications — for example, in the search for extraterrestrial life on exoplanets. However, this measure raises a question that was not addressed by Cronin: under the theory of an unguided process of chemical and biological evolution, should such a threshold of complexity, clearly identifying life and its activities, even be expected? 

I submit that it should not be expected at all. On the contrary, we should expect a smooth grade of complexity between abiotic and biotic processes, that does not allow for a clear distinction in the fuzzy transitional region. The fact that there seems to be a precise level of complexity, above which there is only life and its products and below which there is not, indicates to me a saltational phase transition. Such a transition does not fit with Cronin’s suggestion of an origin through unguided selection mechanisms.

Cronin’s Core Fallacy

A similar intuition seems to have pushed Cronin to commit the core fallacy that struck me in his presentation. I would call it the “If it were not” fallacy, or the fallacy of a ”naturalism of the gaps.” The fallacy admits that we have no clue how life originated. But it suggests that we will just have to wait, maybe for decades more of research, to see the problems solved. These twin fallacies are of course rooted in Cronin’s preferred worldview, which is explicitly one of materialist naturalism.

Cronin does not reason from the evidence with an unbiased inference to the best explanation. Instead, he excludes a priori the alternative of intelligent causation and restricts his search to material causes alone. Here is what Cronin said in his opening statement (timecode 1.04.30-1.04:50): “If we weren’t invented by some, … hmmm …well, if we are not in Elon Musk’s simulation and we are not some other fictitious creation, then there are other processes going on …”. This “If it were not” fallacy is a combination of the fallacy of the excluded middle and the fallacy of begging the question. But Cronin cannot justify his a priori exclusion of design with an appeal to methodological naturalism or to the scientific method. That is because Cronin himself mentioned in his talk fully naturalistic alternatives for intelligent causation such as the simulation hypothesis. 

His fallacy is therefore not rooted in a mere methodological naturalism but rather in a full-fledged ontological naturalism. He explicitly thinks that meaning, purpose, life, consciousness, memory, etc., are all emergent from material processes. In a previous conversation with James Tour he even made the absurd statement, “I don’t think consciousness exists” (see this episode of Unbelievable? with host Justin Brierley at timecode 1:11:28). In the recent debate, Cronin explicitly and unequivocally identified as a materialist, which fully explains his “If it were not“ fallacy and his “naturalism of the gaps.”

Excluding Intelligent Design

In my view this perfectly exemplifies the dynamic in modern science and its mainstream opposition against intelligent design theory: intelligent causation is a priori excluded from the set of allowed hypotheses under the false pretense of methodological naturalism. But this exclusion is actually rooted in ontological naturalism and crude materialism. The latter is an unfalsifiable metaphysical belief that has no justification for serving as an underlying paradigm for science. 

Even worse: the growing consensus in theoretical physics holds that spacetime is not fundamental but emergent from quantum entanglement. This implies an ultimate reality of quantum information beyond space and time. And that clearly contradicts materialism and reveals it to be an obsolete and anachronistic worldview, rooted in a 19th-century picture of a clockwork universe with billiard-ball-like elementary particles. Even if we were to grant for the sake of the argument that methodological naturalism is a core tenet of the scientific method, intelligent design is a valid form of causation that should and ultimately will return to the mainstream of science. When it does, we will be permitted to follow the evidence wherever it leads, without worldview blinders.