For Mises or Rothbard, it is simply confused to posit latent preferences; if two individuals fail to make an exchange, then this ipso facto demonstrates that at that moment at least one of them would not have benefited from the exchange.
Irrespective of all external considerations of right or wrong; absolutely; by the very deed itself It sometimes means the act itself carries the consequences (as excommunication without sentence of excommunication being directly pronounced) "Whatever the captain does is right ipso facto [i e because it is done by the captain], and any opposition to it is wrong, on board ship " - R H Dana By burning the Pope's bull, Luther ipso facto [by the very deed itself] denied the Pope's supremacy Heresy carries excommunication ipso facto
If something is ipso facto true, it must be true, because of a fact that has been mentioned. If a crime occurs then there is, ipso facto, a guilty party. used to show that something is known from or proved by the facts