CF Dictionary · Evaluating Ideas & Arguments
Decisive Argument
An argument that, if accepted, makes its target IGC impossible to accept. CF's preferred kind of argument.
A decisive argument is one that contradicts the negation of its conclusion. If you accept the argument, you must accept its conclusion; you cannot consistently accept both the argument and the negation.
In CF, decisive arguments are split:
- Decisive negative arguments → refutations (decisive criticisms).
- Decisive positive arguments → would prove the IGC. Per CR and CF, these are rare or impossible because of fallibilism.
The crucial point
A "strong" or "weak" label is irrelevant. If an argument decisively refutes an IGC, it counts — full stop. If it doesn't, it counts for nothing, regardless of how compelling it feels.
This is one of CF's most counter-intuitive commitments. In ordinary discourse we say "that was a strong argument" or "the evidence is somewhat weak." CF says these are mistakes. Arguments are digital; they refute or they don't.
Universality loophole
There is one place where decisive positive arguments are accessible: when the premise is a universal. From "all men are mortal" plus "Socrates is a man", you can decisively prove "Socrates is mortal." But this only works because the universal premise itself is fallible — and CF is fallibilist about universals.
"A decisive argument (or group of arguments) contradicts the negation of its conclusion, so both can't be true." — criticalfallibilism.com