Fallacy of the Unknowable Fact
The fallacy treats speculation about the future or an unobserved alternative as an established fact. A forecast or counterfactual is not automatically fallacious; its uncertainty and supporting evidence matter.
THE IDEA
2.8 FALLACY OF THE UNKNOWABLE FACT
The fallacy of the unknowable fact contains as one of its premises a claim that is unknowable. This fallacy uses as evidence a “fact”—often speculation—that cannot be verified at the present time. For example:
- Father to daughter: If you don’t go to college, then you’ll never be successful.
In this example, the father is claiming that he knows what the future holds for his daughter. The father supplies no basis for treating this sweeping prediction as certain. Its outcome cannot be checked now, but that alone does not make every forecast unreasonable.
Consider this example:
- If only Adolf Hitler had a healthy relationship with his parents, World War II would have never occurred.
The example asserts a definite outcome in an alternative history without supporting the causal chain. Historical evidence can inform counterfactual analysis, but it cannot directly reveal what happened in a history that did not occur. Present such conclusions with their assumptions and uncertainty.
Here are two final examples of the fallacy of the unknowable fact:
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I wish I’d gone to dental school instead of majoring in art. I’d be rich now!
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Elizabeth should have married Stan instead of Wayne. She would be so much happier.
When to use it
When evaluating predictions about the outcome of a decision, such as 'If I take this job, I'll be happier.'
In historical analyses that assume alternative outcomes based on changed conditions, e.g., 'If the other candidate had won, the economy would be better.'
When reflecting on personal regrets that involve assumptions about how things would have turned out differently.
FROM THEORY TO EVERYDAY LIFE
In practice
Example 1: College and Success
Father to daughter: If you don’t go to college, then you’ll never be successful.
Example 2: Historical Counterfactual
If only Adolf Hitler had a healthy relationship with his parents, World War II would have never occurred.
Example 3: Career Regret
I wish I’d gone to dental school instead of majoring in art. I’d be rich now!
Example 4: Relationship Regret
Elizabeth should have married Stan instead of Wayne. She would be so much happier.
A MOMENT TO REFLECT
Put it to work.
What are some common arguments you encounter that rely on unverifiable claims about the future?
How can you check whether a premise in an argument is truly unknowable or just uncertain?
Think of a time you made a decision based on a counterfactual claim. Was it justified?
CONTINUE THE CONVERSATION
Source texts
- Informal Logical Fallacies A Brief Guide