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The Lexical Fallacy: Why Appealing to Definitions Is Not an Argument

Summary:
Some arguments never get past semantics. Appealing to the “correct” definition of a word feels like progress, but it’s often a way to avoid the real question. Definitions describe how we use words—they don’t determine what’s true. To reason well, we must move past “word thinking” and talk about ideas, not just terms.

We’ve all seen it happen: someone kills a discussion with, “That’s not what that word means (and you are uneducated).” It sounds smart and final. But arguing from definitions—the so-called lexical fallacy—doesn’t resolve the issue; it replaces reasoning with rhetoric. 1

Scott Adams calls this “word thinking,” where the goal is to win the argument by appealing to official definitions of words instead of thinking through the issues. 2

“Word-thinking is what happens when people try to win an argument by adjusting the definition of words. In these situations there is no appeal to reason.” — Scott Adams

Adams exposes how semantic battles replace logical ones. Once a discussion becomes about who controls the definition, reasoning itself stops. 3

1.0 Why Definitions Can’t Settle Arguments

1.1 The Meaning of Words Depends on Use

The philosopher Ludwig Wittgenstein explained that meaning depends on how words are used in real life, not on abstract definitions. 4

“The meaning of a word is its use in the language.” — Ludwig Wittgenstein, Philosophical Investigations §43 (1953)

Because language is living and contextual, we can’t appeal to a static definition to end a debate. Meaning is dynamic, not dictatorial. 5

1.2 The Definitionist Fallacy

Appealing to dictionaries or etymology to decide questions of truth commits what logicians call the “definitionist fallacy.” 6

“To insist that a word’s meaning be determined solely by a dictionary or an original usage is to commit what logicians sometimes call the definitionist fallacy. Definitions describe usage; they do not decide questions of truth or value.” — Copi, Cohen & McMahon

2.0 Examples of Word Thinking

2.1 Atheism and the “Lack of Belief” Dodge

The Stanford Encyclopedia of Philosophy distinguishes between two kinds of atheism: a psychological form (“the absence of belief in God”) and a philosophical form (“the belief that there is no God”). Both uses are valid descriptively, but when the discussion concerns truth, shifting from the philosophical claim to the personal one becomes a dodge. 7

“‘Atheism’ has been used in both a narrow sense—the belief that there is no God—and a broader sense—the absence of belief in God.” — SEP

As Antony Flew noted,

“To say ‘I do not believe there is a God’ is still to say something about what one thinks the world is like.” 8

Redefining atheism as mere “lack of belief” lets one avoid defending a worldview claim. 9

2.2 Evolution and the Definition That Defines Nothing

Few topics illustrate semantic evasion better than “evolution.” so let me explore it in detail. Evolution’s definitions range from broad and ambiguous “change” to operational measures, to related processes, to a specific and helpful narrow definition. This elasticity allows many to win arguments by conflating distinct meanings. 10

2.2.1 “Change Over Time” — Too Broad to Be Meaningful

The broadest definition — “change over time” — is true but scientifically unhelpful. Everything changes over time—planets, languages, economies, and species. Even extinction and loss of information qualify as “change,” making the phrase compatible with both design and naturalistic views. 11

“Evolution simply means change over time. This broad definition encompasses all of the small and large changes that have shaped life.” — UC Berkeley, Understanding Evolution

Ernst Mayr refined this concept at the population level, defining evolution as

“A change in the genetic composition of a population.” 12

While more technical, this version still describes what happens, not how it happens. It identifies variation, not the origin of complexity, and thus remains descriptive rather than explanatory. 13

2.2.2 “Change in Allele Frequencies” — A Category Error: Measuring, Not Explaining

A narrower, more quantitative form of Mayr’s definition describes evolution:

“Evolution is often defined as change in allele frequencies within a population over time.” — UC Berkeley, Understanding Evolution 14

This definition commits a subtle category error—it treats an operational measure as if it were an explanatory process. Measuring shifts in gene ratios is not the same as identifying the cause of new biological structures. It quantifies population-level variation but says nothing about the origin of the genetic information on which that variation acts.

Shifts in allele frequencies can result from drift, bottlenecks, or loss-of-function mutations—all processes that may reduce complexity. As I’ve argued elsewhere,

“Shifts in allele frequencies are not themselves proof of a creative evolutionary process; they’re only evidence of genetic motion within boundaries.” 15

Operational definitions like this are valuable for tracking change but not for explaining innovation. They measure what varies; they do not identify the causal mechanisms capable of producing new genetic structures or systems. As the Nature Education site observes, mutation is a change in sequence—not a guarantee of functional advancement. 16

2.2.3 “Mutation and Selection” — Related Processes, Not Evolution

Another common phrasing defines evolution as “descent with modification through random mutation and natural selection.” 17 These are real processes, but they are not evolution itself—they are biological mechanisms that influence variation. The debate is not whether they exist but whether they can create the complex, integrated systems of life.

“Natural selection and mutation are real processes; the question is whether their known effects are creative enough to build the complexity of life.” — Stephen C. Meyer, Darwin’s Doubt

Design advocates affirm both mutation and selection, but see them as conservative rather than creative. These mechanisms can fine-tune or preserve existing structures but have not been shown to generate novel functional sequences. Thus, they are congruent with design, not exclusive to naturalism.

2.2.4 “Novel, Functional Genetic Information” — A Definition That Actually Distinguishes

The most useful definition isolates the exclusive, falsifiable claim of Darwinian theory—that unguided natural mechanisms can produce new functional information and biological structures:

Evolution (in the distinct philosophical-scientific sense) is the claim that undirected natural processes—principally random mutation and natural selection—are sufficient to produce the novel proteins, genes, and systems of proteins responsible for the diversity of life’s complex structures.

This definition excludes trivial change (“change over time”), mere metrics (“allele frequency shifts”), and shared processes (mutation and selection). It centers on the real question: Can unguided processes create biological complexity? 18 19

2.3 Faith Has Many Definitions — But Not All Are Equal

Critics often define “faith” in its weakest form—as believing without evidence or submitting to authority without question. That kind of belief exists, and even Scripture warns against it, but it is not the kind of faith that thoughtful Christians defend. 20

As I explained in that article, the word faith covers at least three distinct meanings:

  • Blind Faith — belief held without evidence or against reason; what skeptics rightly reject.
  • Cultural Faith — belief inherited from one’s community or tradition, accepted mainly through upbringing or social belonging.
  • Transformative Faith — belief grounded in evidence, experience, and relationship; a trust that reshapes the person who holds it.

All three definitions are legitimate linguistically, but they are not morally or intellectually equivalent. The first two describe forms of faith that Christians themselves often critique. The third—transformative faith—is the one Scripture and serious theology defend: confidence rooted in knowledge of God’s character and in evidence confirmed through life.

Hebrews 11:1 defines faith this way

“Now faith is the substance of things hoped for, the evidence of things not seen.”

This portrays faith as a rational conviction of unseen realities, grounded in prior evidence – not a blind faith.

C.S. Lewis captured this dynamic precisely:

“Faith is the art of holding on to things your reason has once accepted, in spite of your changing moods.” 21

Transformative faith begins with evidence and reason, grows through trust, and results in personal change. It is informed confidence, not credulous submission. While blind and cultural faiths exist—and their definitions are not false—they are not the faith defended by believers who reason, test, and are transformed by what they believe.

Closing Note

Fighting over definitions is one of the easiest ways to sound intelligent while staying unteachable. Definitions matter, but they don’t end debates—they start them. Real dialogue begins when we stop guarding our dictionaries and start engaging reality.

  1. The Appeal to Definition Fallacy (Effectiviology, 2020)[↩]
  2. Scott Adams, Win Bigly (2017)[↩]
  3. Scott Adams Interview (The Jordan Harbinger Show, 2019)[↩]
  4. Ludwig Wittgenstein (Stanford Encyclopedia of Philosophy, 2018)[↩]
  5. Definitions in Philosophy of Logic (SEP, 2020)[↩]
  6. Copi, Cohen & McMahon, Introduction to Logic (2016)[↩]
  7. Atheism and Agnosticism (SEP, 2019)[↩]
  8. Flew, “The Presumption of Atheism” (1976)[↩]
  9. Sinclair, “Is Atheism Merely a Lack of Belief in God?” (Whole Reason, 2021)[↩]
  10. UC Berkeley: What Is Evolution? (n.d.)[↩]
  11. UC Berkeley (n.d.)[↩]
  12. Mayr, What Evolution Is (2001)[↩]
  13. National Academies: Definitions of Evolutionary Terms (n.d.)[↩]
  14. UC Berkeley, Understanding Evolution (n.d.)[↩]
  15. Sinclair, “No, Shifts in Allele Frequencies Are Not Evolution” (Whole Reason, 2025)[↩]
  16. Nature Education: Genetic Mutation (n.d.)[↩]
  17. Meyer, Darwin’s Doubt (2013)[↩]
  18. Sinclair, “No Shifts in Allele Frequencies Are Not Evolution” (2025)[↩]
  19. Nature Education (n.d.)[↩]
  20. Sinclair, “Three Kinds of Faith” (Whole Reason, 2021)[↩]
  21. C.S. Lewis, Mere Christianity (1952)[↩]
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