Classical Material Implication (→cmi)
- Emphasizes the classical aspect of FDE
- Classical implication
| φ
| ψ
|
| φ → ψ
|
|
| T
| T
|
| T
|
| T
| F
|
| F
|
| F
| T
|
| T
|
| F
| F
|
| T
|
- Designated antecedent ... conditional = consequent, e.g.,
(T → N) = N,
(B → B) = B
- Undesignated antecedent ... conditional = T, e.g.,
(N → N) = T,
(F → B) = T
- FDE and other logics
- FDE restricted to T, N, F is the logic K3
- K3 plus →cmi is synonymous to Ł3
- FDE restricted to T, B, F is the logic LP
- LP plus →cmi is the logic A3
- LP plus contrapostive of →cmi is RM3
- Strange feature ...