What it is
Concluding that something is not the case because it ought not to be.
In the wild
It ought not be true, so it is not.
How to answer it
Keep the description and the evaluation in separate columns.
Values and premises
Moralistic fallacy
Also called Reverse naturalistic fallacy
In depth
Origin and naming
The moralistic fallacy is the naturalistic fallacy's mirror: where one argues from 'is' to 'ought', the other argues from 'ought' to 'is'. Bernard Davis named it in its current sense in a 1978 Nature article resisting calls to restrict basic biological research on the grounds that its findings might be misused — 'knowledge cannot be ensured against misuse, and misuse cannot falsify knowledge.'
More places it shows up
Asked whether a trait shows any heritable component, the committee refuses to fund the study: the question 'shouldn't have an answer', so it can't.
A manager insists the team's workload is fair because an unfair distribution would demoralize everyone — the demoralization is the evidence.
In the comments under a crime stat, someone declares the figure must be fabricated because publishing it would harm the community's reputation.
A parent dismisses the diagnosis because accepting it would mean their child 'was born flawed', which a loving family doesn't do.
How to spot it
- The answer arrives before the question is investigated, and the investigation is the thing being blocked.
- Notice the grammar: 'it can't be true' where the evidence would normally sit.
- The test is what the speaker would do with contrary data — if the answer is 'it must be wrong', you have found it.