Yesterday The Donald proclaimed that, if elected this year, he would get 95% of the African-American vote in 2020. At first blush, this looks like typical Trumpian bushwah; he’s no more likely to get 95% of the African-American vote in any year than he is to become someone’s biological grandmother.
However, the propositional calculus of modern formal logic treats “if-then” statements in a fashion that leads to counter-intuitive results. “If X, then Y,” (formally, X ->Y) is interpreted to mean “It is not the case both that X is true and Y is false” (~[X and ~Y]). In the case where X is sometimes true, there’s no problem; the proposition claims that in all those cases, Y is also true, which is what we naturally mean when we say “if X, then Y.”
But a problem arises when X is always false. In that case, even if Y is never true, it is, indeed, never the case that X is true and Y is false, because it is never the case that X is true. Thus any “if-then” proposition counts as true when the “if” clause is false.
So, assuming that Donald Trump will not, in fact, win the Presidency this year, the claim that, if he were to win, then he would get 95% of the African-American vote in 2020 is also (trivially) true, just like the proposition that, if Trump were to win, then the Persians won Marathon andÂ Ï€ = 3.
Savor this moment; it may be the only instance this year when Donald Trump’s words express a true proposition. And it gives us all one more reason to work hard for the next 80 days: you wouldn’t want to make the poor man a liar, would you?