A paradox of material implication is something that doesn't quite make sense when you look at it. It's like saying two opposite things are both true. A classic example is “If I am short, then I am tall.” It's obviously not true, but we can still write it using material implication. We say “If I am short, then I am tall” which looks like this in logic: (p → q). In the case of this paradox, p and q are both false, so the statement is true even though it doesn't make sense.