One often hears partisans refer to U.S. credibility as something that must be preserved, even treated as a vital interest, something worth fighting for. But there are competing theories on the source of credibility. The two most prominent theories are Current Calculus and Past Actions theories.
Both theories have been tested by rigorous analysis before, always with the same results. The most recent, concise, and convincing examination of Current Calculus and Past Action theories was carried out by Daryl Press a few years back. Rather than public statements made to persuade, Press examined official transcripts and declassified memos documenting high-stakes decision making by U.S., U.K., German, and Russian officials including steps leading to World War II, the Berlin crises, and the Cuban Missile Crisis. The preponderance of evidence aligns with Current Calculus. Scant evidence aligns with Past Actions with the overwhelming preponderance of evidence in opposition.
Consider the recent episode on the Korean Peninsula. If Past Actions theory was correct, little attention would have been paid to the North's threats. If Current Calculus was at work, then the response would be proportional to the North's current ability and interests. The international response was real but measured.
Examining the historical record exposes another interesting finding. Decision makers evaluate the credibility of an opponent's threat -- a declared commitment to use force -- almost entirely by an estimate of the opponent's power to carry out the threat and the importance of the interest involved. Remarkably, however, when deciding to respond to an opponent's threat, decision makers genuinely believe they must act to preserve their own future credibility in the eyes of enemies and friends. In other words, decision makers subscribe to Current Calculus theory but incorrectly believe their opponent's subscribe to Past Actions theory. Go figure.
What's the point? There are many reasons for the U.S. to intervene around the world. Fighting to assure future U.S. credibility isn't one of them. In any given crisis, friends and enemies will assess U.S. credibility at its highest when its vital interests are at stake and when U.S. military power can compel the desired political outcome. Credibility will be at its lowest when only peripheral interests are at stake and when political objectives are beyond the limits of U.S. military power. Yes, there are limits to military power.
To a scientist, a theory contradicted by evidence ceases to be a theory. It must be abandoned, revised, or its application narrowed. Beliefs, on the other hand, can survive, even flourish, in the absence of evidence and even in opposition to the evidence. Past Actions theory, refuted by rigorous analysis, should be considered a belief. Believing doesn't make it so.
Despite evidence to the contrary, the Past Actions belief will remain a powerful rhetorical tool. But when you hear politicians and pundits encourage war to preserve U.S. credibility, demand a better reason.