Philosophy can be quite challenging!

I recently encountered a captivating piece by Gerald R. Baron discussing the foundational assumptions of physicality in modern science. He argues that scientists often mistakenly assume there is no underlying purpose behind physical laws, using Charles Darwin’s quote about his “horrid doubt” as a pivotal point.

As a biologist specializing in molecular genetics and biochemistry, particularly in how yeast cells grow and reproduce, I identify strongly with materialism, assuming no inherent purpose exists within the physical world and its governing laws. While I appreciate the philosophical discourse related to my field, I often find it complex and beyond my grasp—philosophy is indeed challenging!

However, engaging in philosophical debate is not my intention here, as I lack the expertise to do so.

My goal is more modest: to defend the notion of doubt, to contextualize Darwin’s expression of uncertainty, and to clarify what I perceive to be a significant misinterpretation of his “horrid doubt” remark:

> “But then with me 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 anyone trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?…”

The Illusion of Absolute Right and Wrong in Science and the Value of Doubt

As might be anticipated given my background, I have read Darwin’s On the Origin of Species twice, along with Janet Browne’s two-volume biography of him. While I wouldn’t consider myself the most ardent admirer, I find it remarkable how accurate Darwin was, despite the limited knowledge of his time, and conversely, how often he was mistaken.

I address the false dichotomy of right and wrong in science in a recent discussion about the dating of mitochondrial Eve.

Regardless of the accuracy of some specific ideas he proposed, Darwin’s theory of evolution through variation and natural selection remains the cornerstone of biology. The fact that he achieved such significant insights without the advantage of genetics or molecular biology is a testament to the humanities. A similar case applies to Gregor Mendel, who discovered genetic principles around the same period, albeit with his own set of errors and limitations. This parallels the influence of Isaac Newton’s laws of motion and gravity, which propelled modern engineering, despite their limitations later addressed by Einstein’s theory of general relativity (for instance, the peculiarities of Mercury’s orbit near the Sun’s gravity well).

Today, no biologist regards Darwin’s landmark work as the definitive understanding of evolution, nor do they hold him accountable for the errors corrected since its publication.

If someone as brilliant as Darwin could be wrong on numerous aspects, how mistaken might we each be regarding our own ideas?

One of the most notable revisions to classical Darwinism was Stephen J. Gould and Niles Eldredge’s Punctuated Equilibrium hypothesis, which proposed that species remain relatively unchanged for extended geological periods under stable environmental conditions, only to experience rapid evolutionary shifts during significant changes. This theory was supported by fossil evidence, contrasting sharply with Darwin’s notions of constant gradual change.

Currently, Punctuated Equilibrium itself is being scrutinized and revised, exemplifying the dynamic nature of scientific inquiry.

Ideally, no one clings rigidly to outdated theories, regardless of their historical significance or the stature of their proponents. Science embodies a process of evolution—be it gradual or punctuated.

In reality, however, humans often become attached to their own ideas, losing the capacity for self-doubt. Emerging scientists frequently have to wait for the literal passing of the “old guard” for their new theories to receive fair consideration and rigorous testing. Established figures tend to favor their longstanding beliefs, often maintaining control over the direction of research.

Doubt should not be viewed as a flaw in science.

Rather, it ought to be a fundamental characteristic of scientific exploration and our daily behaviors. This inherent doubt can also be termed humility. (Conversely, being paralyzed by doubt is a neurosis; we must act decisively despite our uncertainties, employing strategies such as ongoing data collection and the readiness to adapt based on new information.)

Hopefully, there is an emerging understanding that effective science is not simply about being correct or incorrect. It revolves around the usefulness of theories. If a theory can accurately and reliably predict future occurrences, it retains its value; otherwise, it is either discarded or modified based on its alignment with reality. As humans, we tend to assign a binary classification of right or wrong to ideas that are either upheld or rejected. However, science, in many respects, is objective and unemotional. Right and wrong are not the appropriate measures.

The crux of the matter is that a healthy skepticism underpins the evaluation of a theory’s usefulness and its predictive capabilities, ensuring that a competent scientist remains flexible and open-minded.

Darwin’s Doubts: A Genuine Reflection of Scientific Humility

Many misinterpret Darwin’s “horrid doubts” quote, taking it out of context. In 1881, William Graham wrote The Creed of Science, criticizing a perceived religious conviction inherent in Darwin and his supporters’ views on evolution. In response, Darwin penned a letter to Graham, commending his book and articulating his own profound uncertainties.

To grasp the context of Darwin’s “horrid doubt,” please refer to his brief letter to Graham dated July 3, 1881.

Notably, in the opening of his letter, Darwin emphasized:

> “… there are some points in your book which I cannot digest. The chief one is that the existence of so-called natural laws implies purpose. I cannot see this. Not to mention that many expect that the several great laws will someday be found to follow inevitably from some one single law, yet taking the laws as we now know them, and look at the moon, where the law of gravitation — and no doubt of the conservation of energy — of the atomic theory, &c. &c. hold good, and I cannot see that there is then necessarily any purpose. …”

Let’s reiterate Darwin’s crucial assertion: There is no purpose behind natural laws.

It is within this framework that Darwin further communicates to Graham:

> “… But I have had no practice in abstract reasoning, and I may be all astray. Nevertheless, you have expressed my inward conviction, though far more vividly and clearly than I could have done, that the Universe is not the result of chance. But then with me 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 anyone trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?…”

Importantly, Darwin concurs with Graham’s belief that the universe is not random, but rather directed and purposeful!

Now, can you see? It becomes evident why Darwin experiences his horrid doubt. His doubt reveals his own beliefs that the universe is directed and not merely a product of chance. He questions the existence of purpose beyond the laws of physics, casting doubt on his own convictions regarding purpose and direction in the universe… because his intellect is derived from that of a monkey.

Despite his considerable intellect, Darwin rightly questions his own deepest beliefs due to the understanding that he, like the rest of us, is an evolved primate whose thoughts are prone to error. Our most brilliant ideas are inherently unreliable.

To derive knowledge and conclusions from internal convictions, Darwin suggests, is a pathway to becoming overly simplistic. Genuine knowledge must stem from external evidence, from observations and empirical testing of the natural world.

His “horrid doubt” serves as a manifestation of humility and skepticism toward an esteemed peer who shares similar convictions.

This letter was not an isolated instance of Darwin’s humility; throughout his career, he exhibited a consistent modesty. Notably, he spent decades refining and questioning his theory of evolution, resisting numerous entreaties from friends and colleagues to publish—until he was compelled to do so upon discovering that someone else had developed a similar theory. This humility and uncertainty resonate in his correspondence with Graham. Nevertheless, his stance is clear: he perceives no purpose driving physical laws.

Was Darwin Correct?

A natural question arises: did Darwin correctly assert that there is no purpose behind physical laws? Importantly, note how Darwin articulated his position to Graham: “I cannot see this.” He did not claim the absence of purpose as a definitive truth; rather, he stated that he could not observe evidence supporting the notion of purpose behind natural laws.

Darwin’s stance against Graham—“I cannot see this”—was neither a fact nor a conclusion, nor even a firm belief. In fact, his conviction aligned with Graham’s, but Darwin’s reliance on empirical data led him to a different conclusion regarding the existence of purpose behind natural laws.

Darwin exemplified the behavior of a good scientist when his data did not support his previously held beliefs or favored hypotheses: he rejected the conviction. However, he did so with humility, acknowledging that his understanding could be flawed, expressing it as “I cannot see this” instead of declaring “this is incorrect.”

Thank you for reading, and please share!

If you found this discussion engaging, I invite you to explore my reflections on empathizing with animals here:

And if you appreciated the Darwin perspective, you might enjoy my insights on his achievements as a scientist during the Victorian era here: