Questions concerning the nature of evolution—questions which find their way into discourse time and again—have cropped up yet again. This post will make an effort to outline some of these issues, with view to fostering a fruitful discussion for our Philosophical Happy Hour (24 April 2024) on how we ought to think of evolution. It is probably best, however, if we begin with a definition of evolution.

While the theory of evolution finds itself applied most often and most successfully within the field of biology, it has been extended to describe the advent of any new form or diversity of being arising by a gradual process of change throughout the entire cosmos. As described by experts during the 1959 Darwin Centennial Celebration:

Evolution is definable in general terms as a one-way irreversible process in time, which during its course generates novelty, diversity, and higher levels of organization. It operates in all sectors of the phenomenal universe but has been most fully described and analyzed in the biological sector.

1960: Evolution after Darwin, 107; cited in Nogar 1963: The Wisdom of Evolution, 30.

Thus, “evolution” so-understood signifies not only the unfolding of life’s variation, but of the whole cosmos.

In a way, this turn in terminology—a century after Darwin’s Origin of Species—returns the word “evolution” to the broader (if yet-more-specifically-applied) meaning that it had prior to the 18th century: for the word, from Latin ex- (out, from) and volvere (to roll, and thus, a rolling-out or unrolling, unfolding), can be conceived as a general description. Yet this return obscures a certain confusion. For the most difficult problem of biological evolution—considered precisely as a scientific theory—consists in identifying the means by which evolution occurs. But presumably, the biological mechanisms affecting a diversity of species will not apply to the differentiation of gasses, solids, galaxies, stars and planets, and so on.

The following sections elaborate on some of the particularly controversial issues.

Evolution, Science, and Scientism

To attain clarity in our understanding of evolution, therefore, let us ask a few further questions. First: is biological evolution scientifically decided? Many today treat it as a given. (It has always struck me that the philosopher John Searle, in his 2009: Making the Social World on p.4 writes “We need to show how all the other parts of reality are dependent on, and in various ways derive from, the basic facts. For our purposes the two most fundamental sets of basic facts are the atomic theory of matter and the evolutionary theory of biology.”) This treatment, combined with ignorance of the actual mechanisms or complexities involved, situates evolution as a matter of ideology. It takes little thought to comprehend the significance of the progression of figures in the image below. It takes far more to grasp the supposed explanatory principles at work, as it were, in the gaps.

The Science of Evolution

That said, scientists across multiple disciplines have collected much evidence in support of the theory of evolution. For instance: the fossil record, genetic similarities across species (common ancestors); biogeographical differentiation (variation between species in Africa and the Galapagos, for instance); adaptive homologous structures (comparable structures like arms and wings adapted to diverse functions in different species), embryological similarities (there being, e.g., aquatic-functioning structures such as gill-slits in land-bound vertebrate creatures while in an embryonic state); and adaptive organistic responses (bacterial antibiotic resistance, finch beak sizes). Some of these are clear indications of genetic variation in DNA across generations (genotypic variation that is evolution proper); others of epigenetic differentiation in how species behave (phenotypic variation). The relations between these two forms of differentiation remain unclear.

Put otherwise, strong evidence for biological evolution exists. Yet the mechanisms of how it actually unfolds remain in hypotheses far from verification. We know that genotypic variation occurs through mutations in the DNA sequence during replication or through environmental factors. Sexual reproduction shuffles genetic material (“recombination”), especially notable when migrating populations become intermingled (“genetic flow”). The greater heterogeneity in the genetic constitution of a population, the more likely that population is to develop adaptively to the environment, and vice versa (“genetic drift”). Yet the precise interplay of these factors hides from our view.

The Ideological Appropriation of Evolution

Throughout the 20th century and into the first quarter of the 21st, anti-religious thinkers have used evolution as a cudgel against faith. To exemplify this ideological appropriation, we can consider the works of Richard Dawkins and (may he rest in peace), Daniel Dennett—two figures prominent in the so-called “New Atheism” movement.

Dawkins, most famous for his 2006 book, The God Delusion, extensively employs evolution within this work as an argument against belief in God. At the heart of this argument, one finds the idea of “natural selection”. Succinctly defined, natural selection is held as the process by which organisms having traits better suited to their environments are more likely to survive and reproduce, leading to gradual evolutionary adaptation over long stretches of time. For Dawkins, natural explanation functions as a narrative device explaining the complexity and diversity of the universe, and that, through this principle, small changes over a long enough time can lead to improbable conclusions.

Dennett in his 1995 Darwin’s Dangerous Idea, comparably, considers natural selection as a kind of “background algorithm” to life as a whole, explanatory not only of biological evolution but cultural development. The random variation of genetic differentiation, given enough iterations, leads to greater successes over time.

In both thinkers, we see an explanation of complex phenomena by the interaction of mere vires a tergo: in other words, “forces from the past”. As I will explain below, this relies upon a Procrustean limitation of causality. But for now, we can say that the vis a tergo evolutionary conception posits the universe as deterministic. Armed with a deterministic theory, these ideologues hammer away at the uniqueness and specialness of human beings and religious belief as efforts at escaping the inevitable material strictures of our existence.

Evolution, Religion, and Opposition

Dennett and Dawkins, along with their atheistic cohorts and followers, realize an old opposition and exacerbate a reactionary posture already present in those opposed to the idea of evolution.  That is, in the late 19th and early 20th centuries, as Theodosius Dobzhansky put it, “Darwin’s theory of evolution seemed to many… offensive to human dignity and incompatible with their religious faith.” (Foreword to Nogar 1963: The Wisdom of Evolution, 12.) The idea of a universal evolution, as applied in denial that the human being possesses a unique spiritual soul, denies that the human being is made in the image and likeness of God.

It is important to realize, however, that the scientific theory of evolution itself unfolded within what could be called a philosophically bankrupt time.  Between the dominance of modern nominalistic theories of knowledge and the 18th and 19th century rejections of Scholastic thinking in the university generally (and specifically among Protestants), reconciling the idea of evolution with religious faith seemed not only problematic, but near-impossible.  Faith and its practice, in other words, became increasingly constrained to a position of supposed “subjective” opinion. 

Because truth cannot contradict truth, the apparent irreconcilability of belief in the literal truth of revelation and the theory of evolution led to believers outright denying the latter.  Some, such as Ken Ham or Henry Morris, adhere to the position that any purported science in contradiction to literal interpretations of scripture are, de facto, inaccurate.  Others, such as Michael Behe or William Dembski, advocate for intelligent design as an alternative, claiming that the evident complexity of the cosmos requires a cause independent of that cosmos itself. 

Within the Catholic tradition, Fr. Chad Ripperger authored a treatise on The Matphysics of Evolution: Evolutionary Theory in Light of First Principles which, taking up Aristotelian principles (see more below) argues that not only theological considerations but also philosophical ones contradict the theory of evolution.  For decades, the Kolbe Center for the Study of Creation has dedicated itself to dismantling evolution as a theory inimical to faith.

The Origins of Man

As aforementioned, the central difficulty concerns the development of the human being.  Long has it been the orthodox view of all Christian believers that God directly infuses the spiritual soul of the human person at conception, and that this infusion alone suffices to explain our uniquely spiritual mode of existence.  The theory of evolution, which explains the development of the human as a consequence of genetic mutations from simpler to more complex forms of life, proceeding through the line of primates and eventually resulting in homo sapiens, seems to contradict this Christian understanding.

Even the most ardent students of evolution must admit (so long as they are not caught in a converse ideology) that the evidence heretofore collected does not demonstrate such a development to have happened.  At best, it indicates its possibility.  That many of the remains purportedly demonstrating links between lower primates and advanced forms of human bodies have been proven hoaxes or mistakes undermines confidence in the theory as well.  Indeed, the empirical evidence—as is always the case—never demonstrates its own meaning, but always requires interpretation.  Under or through what narratives are we to understand the things we see and discover?

Interpretation and the Weaponization of Theory

On the one hand, we touch here upon matters clearly beyond our scope—such as, “how may one interpret the creation narratives of Sacred Scripture?”  On the other hand, we ought to note that opposition to theories proposed by modern science stemming from their contradiction to faith is to put the sources of revelation at odds with one another.  Thinkers like Dawkins and Dennett posit the same opposition, from the other side: opposing faith because it contradicts their senses.  If we accept the terms of this opposition we are condemned to choose a side, and, choosing a side, to divide and fragment our cosmos.

Others who have attempted to affect a cohesion between the science of evolution and faith in creation—including controversial figures like Pierre Teilhard de Chardin, SJ or Raymond Nogar, OP—have been met with criticism from both sides.  A figure seen as heterodox by either force will be grouped by them with the opposition and therefore seldom heard.  Those proposing a third way, most often, are challenging figures.

But such a challenge proves today most necessary.  So easily do many become seized in ideological commitments without realization.  Those held by opposed ideologies do naught to break this grasp, but, rather—for the most part—only strengthen it.

Evolution, Truth, and Aristotelian Philosophy

The resolution of this difficulty, it seems to me, can only be attained through a genuine philosophical habit.  (Note that a resolution of the difficulty is not the same as the solution to a problem.)  Most especially, we appear in want of a deeper and improved understanding of causality.  Those who weaponize evolution against faith do so with a Procrustean notion of causality: accepting only one kind of causal relation, namely, that between the efficient and the material.  Evacuating causality of the formal and final sets the debate in terms inescapably in their favor. But our understanding of any phenomenon, bereft of a full causal schema, proves incomplete.

By contrast, some—such as Fr. Ripperger—attempt rigorously to employ an Aristotelian causal model in denying the possibility of evolution.  Invoking principles of sufficient reason, proportionate causality, and finality, Fr. Ripperger argues that the notion is philosophically inadmissible from the Aristotelian-Thomistic perspective.  The first two—sufficient reason and proportionate causality—appear most central to his objection. 

Succinctly stated, these are, first, the principle that a sufficient reason must be established to explain how any thing (whether a separate being or an intrinsic principle) is responsible for another.  For instance, if a weak tap against a wooden wall results in the collapse of the wall, one will look for another cause—the tap being insufficiently forceful—and thus discover termite damage.  Second, proportionate causality holds that an effect cannot be greater than its cause.  If I throw a ball and it moves at a velocity greater than the force transferred to it by my arm, we would have to discover some other cause responsible for this.

Principles of Causality

Applying these two principles in argument against evolution does not prove difficult: how can a lesser prior generation give rise to a posterior generation which is greater (i.e., evolutionary development denied by proportionate causality)?  And how can a specifying form not in a prior generation come to arise in a later (i.e., speciation denied by sufficient reason)?

But this opinion, too, consists in a certain interpretation: not only of what Aristotle and St. Thomas mean in their conceptions of essence, existence, substance, accident, species, form, final cause, and so on, but also of the realities signified by these conceptions.  More poignantly, his conception of causality appears rather narrow: not only with respect to the specification of form but also with respect to the force of the final.  Put in other words, Fr. Ripperger no less than Dawkins or Dennett considers the theory of evolution solely on grounds of the vires a tergo.  He limits final causality to a thing’s pursuit of formal perfection. Likewise, he limits formal causality to the intrinsic and primarily substantial essence of things.

Questions to Pursue

This post could be expanded a hundredfold quite easily (but for the constraints of time).  But hopefully it has illustrated some of the difficulty that stands in need of resolution.  As such, we would like to propose the following questions for discussion:

1. Does Aristotelian philosophy necessarily oppose the theory of evolution?  Are the principles of sufficient reason or proportionate causality genuinely opposed to the theory?
2. Can facts definitively establish the truth or falsity of evolutionary theory?
3. What is form as a principle of life?  How is form transferred from one generation to the next?  In what ways does material receptivity affect this generational transference of form?
4. Do we need a more robust understanding of causality to interpret the proposed mechanisms of evolutionary development in light of Aristotelian philosophical principles?

We are open to these questions branching out into other areas!  Please join us this Wednesday.