Toolkit · Inference · No. 40
Editorial illustration for Debunking explanation

Debunking explanation

from 1841 Feuerbach and Marx; the modern evolutionary form is from the 1980s

Explain why people hold the belief in a way that has nothing to do with its being true, and the support the belief seemed to have quietly disappears.

Active
from 1841
Where
Germany, later Australia and the United States
Status
In use
Difficulty
Power
Rigour
Reach
Relevance

What it is

A debunking argument does not show a belief is false. It offers a complete causal explanation of why the belief is held that makes no reference to its truth, and argues that the belief therefore has no support from the fact that people hold it.

The target is the evidential value of the belief's popularity or persistence, not the belief itself. That distinction is constantly lost, and losing it is what turns the argument into a fallacy.

How it works

Identify the belief and what it is thought to gain from being widely held. Give a full causal account of why it is held. Show that the account does not require the belief to be true. Conclude that its being held is no evidence for it.

The third step is where the argument is won. If the best explanation of why people believe it is that it is true and they noticed, nothing has been debunked.

The form of the inference

  1. The belief is held widely, and this is treated as supporting it
  2. Here is a full causal explanation of why it is held
  3. The explanation nowhere requires the belief to be true
  4. Therefore its being held provides no support for it
  5. The belief may still be true, on other grounds

The argument

Proposition The fact that we have always used this supplier is not a reason to keep using them.

  1. The committee's stated ground for renewing is that thirty years of continuous use shows the supplier is the best available.
  2. The full explanation of the thirty years is this: the original selection in 1994 was made by a chair with a family connection, renewal has never required a tender because the contract falls under the threshold, and each renewal cited the previous one as evidence of satisfaction.
  3. At no point in that chain did anyone compare the supplier against an alternative.
  4. So the explanation of the thirty-year record does not require the supplier to be the best available; it requires only that nobody ever checked.
  5. The record is therefore not evidence of quality, whatever else it may be.

Therefore The longevity of the arrangement gives no support to the claim that the supplier is the best available, and the committee must find some other ground or run a tender.

Nothing here says the supplier is bad. They may well be excellent. What has been removed is the only reason the committee gave, which is exactly what a debunking argument does and all it does.

What it is good for

Any belief whose main support is that it is widely or long held. It is the sharpest instrument available against tradition, consensus and intuition offered as evidence.

Where it fails

It slides into the genetic fallacy constantly. Showing why a belief arose is not showing it false, and the step from *this explanation does not require truth* to *therefore false* is invalid — but it is made so often that the whole form is regarded with suspicion.

It also generalises dangerously. Every belief anyone holds has a causal history that can be told without mentioning truth, including the debunker's own, and if the argument works everywhere it destroys itself along with its targets. Confining it requires a principled account of when a causal history undercuts and when it does not, and nobody has one.

Common misconceptions

That it refutes the belief. It removes one line of support. The belief may be true and may have other support, and a careful debunker says so.

Where it came from

Feuerbach explains religion as projected human nature in 1841; Marx and Nietzsche give the pattern its enduring form. The contemporary version arrived in the 1980s with evolutionary explanations of moral intuition.

What became of it

Now a standard argument type in metaethics, philosophy of religion and epistemology, with the self-undermining problem as its permanent open question.

Lasting influence

Street's evolutionary debunking argument against moral realism is the most discussed version, and the shape recurs throughout the sociology of knowledge.

Why it still matters

High, and rising as evolutionary explanations of belief have become available.

Put another way

Finding that the witness was paid. The testimony might still be true, and it is no longer evidence.

Texts

Sharon Street, A Darwinian Dilemma for Realist Theories of Value

The clearest modern statement, and the one that forced metaethics to take the form seriously.

Where to start

Read Street, then try to state a principle that stops the argument applying to your own beliefs. The difficulty is the point.

The surprising bit

The argument is hardest to contain precisely where it is strongest, since the debunker's own beliefs have causal histories of exactly the same kind.

In their own words

Man makes religion, religion does not make man

Karl Marx

Who held it

Sharon Street

Connections

Relies on
Abduction
Set against
Endoxa
Parallel to
Genealogy

The verdict

Devastating against appeals to tradition and consensus, and one short invalid step away from a fallacy.

Sources