Bush’s bad logic

David Frum explains the train of thought behind a presidential speech:

a) Tyranny leads to resentment.

b) Resentment breeds ideologies that excuse murder.

c) Murderers will seek the deadliest weapons they can find.

d) Those weapons can threaten the American homeland.

e) Therefore: American security requires the US to help defeat tyranny and promote freedom in other lands.

(a) and (b) are true. However, the chain breaks down at (c), as this is demonstrably untrue. Murderers almost never seek the deadliest weapons they can find, but rather, make use of those which come most easily to hand. A fifty-caliber Desert Eagle is far deadlier than a cheap 9mm or bare hands, but more people are murdered by 9mm and bare hands than by large caliber weaponry.

Since (c) is false, the chain is broken, (d) and (e) are therefore false and need not be considered.

It’s not surprising that the administration is incapable of basic logic, but it’s interesting to see one of its crudely constructed arguments laid out so clearly by a former participant in the process.