The epistemic conception of vagueness
- Stoic logicians?
- Late 1980s and early 1990s - Roy Sorensen and Paul Horwich
- Timothy Williamson
Argument from T-schema
No sentence that says something is neither true nor false.
- u says that p
- It is not the case that: u is true or u is false.
- If u says that p, then u is true iff p
- If u says that p, then u is false iff ¬p
- u is true iff p (MP 1,3)
- u is false iff ¬p (MP 1,3)
- It is not the case that: p or u is false. (Substitution 2,5)
- It is not the case that: p or ¬p (Substitution 6,7)
- ¬p and ¬¬p (De Morgan 8)
Margin of error
Higher order vagueness
If vague concepts really do have sharp boundaries, what determines where those boundaries lie?