trilemma

A circumstance in which a choice must be made between three options that seem equally undesirable.

With all these dilemmas and trilemmas crowding the mind, if one did not know better, one might be tempted to doubt whether any such versions were ever made at all.

A situation in which a choice must be made among three desirable options, only two of which are possible at the same time.

At the most general level, policymakers in open economies face a macroeconomic trilemma: 1. to stabilize the exchange rate; 2. to enjoy free international capital mobility; 3. to engage in a monetary policy oriented toward domestic goals. Because only two out of the three objectives can be mutually consistent, policymakers must decide which one to give up.

The UK government has forced itself into a trilemma in which it has adopted three positions, only two of which can be achieved at any one time: to avoid a hard border within the island of Ireland; for the UK as whole to leave both the customs union and the single market; and to rule out any special arrangements for Northern Ireland in relation to a customs union and single market.

An argument containing three alternatives, jointly exhaustive either under any condition(s) or under all condition(s) consistent with the universe of discourse of that argument, that each imply the same conclusion.

It has been remarked as a characteristic of the late Sir Robert Peel, that in introducing his measures to the House of Commons, he often used the trilemma. "Three courses are before us—to go backward, to stand still, to go forward. We cannot go backward; we cannot stand still; we must, then, go forward."

And in anticipation of it, while he [Johann Joseph Ignaz von Döllinger] declares at one moment that it would be profane to limit Divine Providence to an alternative, he affirms in the next that there can be no harm whatever in shutting it up to a supposed exhaustive trilemma.