The empirical logic used, however, is often quite twisted. Here's Cato's Dan Mitchell with an analogy:
Next time I see my buddies, I’m going to claim that I enjoyed a week of debauchery with the Victoria’s Secret models. And if any of them are rude enough to point out that I’m lying, I’ll simply explain that I started with an assumption of spending -7 nights with the supermodels. And since I actually spent zero nights with them, that means a net of +7. Some of you may be wondering whether it makes sense to begin with an assumption of “-7 nights,” but I figure that’s okay since Keynesians begin with the assumption that you can increase your prosperity by transferring money from your left pocket to your right pocket.