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Frank Visser, graduated as a psychologist of culture and religion, founded IntegralWorld in 1997. He worked as production manager for various publishing houses and as service manager for various internet companies and lives in Amsterdam. Books: Ken Wilber: Thought as Passion (SUNY, 2003), and The Corona Conspiracy: Combatting Disinformation about the Coronavirus (Kindle, 2020).

Common Design vs. Common Descent

Competing Explanations or a False Symmetry?

Frank Visser / ChatGPT

Introduction

Creationists and proponents of Intelligent Design (ID) frequently argue that common design is just as plausible as common descent in explaining the diversity and similarity of life forms. According to this view, shared anatomical structures, genetic sequences, and biochemical pathways could just as easily reflect the reuse of successful design templates by an intelligent agent as inheritance from common ancestors. The dispute is often framed as a paradigmatic standoff: two worldviews interpreting the same data differently, neither decisively refutable.

This essay argues that this framing is misleading. While “common design” is logically possible, it fails as a scientific explanation when evaluated by standard criteria of explanatory power, predictive capacity, consilience, and methodological economy. The issue is not undecidability between paradigms, but asymmetry in evidential support.

What Common Descent Actually Explains

Common descent is not a vague metaphysical claim that “organisms are related.” It is a historically specific hypothesis: life diversified through branching lineages over time, with inherited variation shaped by population-level processes such as mutation, selection, drift, and constraint.

Crucially, this hypothesis generates risky predictions:

• Nested hierarchies of traits, both morphological and genetic

• Congruence across independent datasets (fossils, anatomy, embryology, biogeography, molecular phylogenetics)

• Imperfect, jury-rigged structures reflecting historical constraint rather than optimal engineering

• Nonfunctional or maladaptive features preserved by inheritance (vestigial organs, pseudogenes, endogenous retroviruses)

• Transitional forms in both morphology and genomes

These predictions were articulated before many of the relevant data were discovered—most notably in molecular biology, where DNA comparisons later confirmed phylogenetic trees inferred from anatomy.

The Elasticity of “Common Design”

By contrast, “common design” is not a single hypothesis but an umbrella for many unspecified possibilities:

• The designer may value efficiency, beauty, reuse, symbolic meaning, or inscrutable goals.

• Similarity may be intentional, incidental, or deceptive.

• Differences may reflect functional necessity, aesthetic choice, or testing variation.

Because the designer's intentions are unconstrained, any pattern of similarity or difference is compatible with common design. This elasticity is its central weakness.

Where common descent predicts nested hierarchies, common design can only accommodate them post hoc. Where descent predicts broken genes in shared locations, design must invoke mysterious reasons for deliberately copying nonfunctional or harmful elements.

In short, common design explains everything by explaining nothing in particular.

The Problem of Bad Design

One of the strongest asymmetries concerns biological imperfection.

Examples abound:

• The recurrent laryngeal nerve in mammals, which takes a long detour around the aorta.

• The human eye's inverted retina, creating a blind spot.

• Shared pseudogenes for vitamin C synthesis in primates.

• Endogenous retroviral insertions at identical genomic locations across species.

Under common descent, these are precisely what we expect from historical inheritance with modification. Under common design, they require ad hoc rationalizations: perhaps the designer reused flawed modules, or intended inefficiency for unknown reasons.

Invoking a designer who intentionally embeds broken features indistinguishable from evolutionary leftovers collapses the distinction between design and descent as explanatory categories.

Paradigms and the Myth of Undecidability

Creationists often appeal to philosophy of science, suggesting this is a Kuhnian paradigm clash in which evidence is theory-laden and decisive proof impossible.

This overstates Kuhn and understates scientific practice.

Paradigms are not sealed belief systems immune to evidence. They are evaluated by:

• Internal coherence

• Predictive success

• Unification of disparate facts

• Reduction of auxiliary assumptions

By these criteria, common descent is overwhelmingly superior. It unifies biology under a single historical framework, while common design fragments explanation into countless untestable intentions.

Undecidability applies when two frameworks make equally precise, equally successful predictions. That is not the case here.

Why “Equal Plausibility” Is a Rhetorical Move

The claim that common design is “just as plausible” relies on lowering the bar for explanation:

• Logical possibility is conflated with scientific plausibility.

• After-the-fact accommodation is mistaken for prediction.

• Methodological naturalism is portrayed as ideological bias rather than a success condition.

If common design were treated with the same evidential standards as common descent, it would need to specify why designs follow genealogical patterns, why errors are inherited in nested fashion, and why the designer's actions mimic evolutionary history so precisely.

No such theory exists.

Conclusion

The debate between common descent and common design is not a genuine stalemate between two equally supported paradigms. Common descent is a robust, testable, and unifying explanation that has repeatedly survived empirical challenge and generated successful predictions across multiple disciplines.

Common design, by contrast, functions as a permissive interpretive overlay—logically possible but scientifically inert. It does not compete with common descent on explanatory grounds; it merely coexists by refusing to specify conditions under which it could fail.

The issue, therefore, is not undecidability. It is the difference between an explanation that earns its authority through constraint and evidence, and one that preserves plausibility only by remaining unconstrained.

In science, that difference is decisive.