An explosionist is
one who believes that any statement follows from a contradiction. Here’s an
argument for explosionism:
1 A • ~A ∴ B
2 A 1,
conjunction elimination (•E)
3 A v
B 2, disjunction introduction (vI)
4 ~A 1, •E
5 B 3, 4, disjunctive syllogism (DS)
Thus, if one wishes to be an anti-explosionist, one must say
that either •E, vI, or DS is invalid.1
According to John Bell and company, explosionism follows
from bivalence:
Proposition
1.1 If P1,…, Pn╞
Q,
then the set {P1,…, Pn, ~Q} is unsatisfiable [i.e. a
contradiction], and
conversely.
For to say that {P1,…, Pn, ~Q} is unsatisfiable is just to assert that P1,…, Pn, and ~Q are never simultaneously true, which,
given the principle of bivalence, amounts to asserting that ~Q is
false, i.e. Q is true, whenever all
of P1,…, Pn are.
In particular, it follows that if
{P1,…, Pn} is unsatisfiable, P1,…, Pn╞ Q, for any statement Q. That is, inconsistent
premises yield any conclusion whatsoever.2
How so, exactly? How exactly does
explosionism follow form bivalence?
1
A • ~A ∴ B
2
A v ~A (bivalence)
3
B v ~B (bivalence)
4
????
1
If I were an anti-explosionist, I would deny vI. Many anti-explosionists deny DS
rather than vI. I am utterly
baffled by such anti-explosionists.
2
John Bell, David DeVidi, and Graham Solomon, Logical Options (Toronto: Broadview Press, 2001), 14. Emphasis is
Bell’s et al.