The Swap Test

The swap test is this site's name for a way of reading a moral dilemma. Change one condition whose moral relevance is disputed, list the other factors that changed along with it, and then ask whether the judgment changes.

How the swap test works

Take a named dilemma and pick one condition people argue about, such as whether the person affected is a stranger or a family member, or whether they are near or far away. Swap only that condition and keep everything else as close to the original as the scenario allows.

A swap rarely changes just one thing. Making the person a family member may also change how much you know about them and which obligations are in play. The swap test lists those side effects in the same row as the swap, so that a changed judgment is not credited to the one condition alone.

Each row of a swap-test table then says what its judgment rests on. There are three possibilities:

• Your own answer. The row asks the question and leaves the judgment to you.
• A published experiment. The row gives the source, the sample size and the year, and reports only what that study measured under its own conditions.
• The site's hypothesis. The row is marked [hypothesis], and you can disagree with it.

Three dilemma entries carry such a table. In the prisoner's dilemma, five swaps, from a repeated game to a fixed rule as the other player, are left to your own answer, and the sixth, two firms keeping a price high, is marked [hypothesis]. The experience machine table works the same way: five rows are yours to answer, and the row that changes how well things are going for you now is marked [hypothesis]. The veil of ignorance is the only one of the three with published experiments: two rows report group choices from Frohlich and Oppenheimer's lab studies, five are left to you, and one is marked [hypothesis].

What the swap test can and cannot show

When no measured result is available, the most a row can say is that the swap, together with whatever changed with it, may affect the judgment. A single changed judgment does not show which detail the judgment depends on, and the swap test is not used to claim that it does.

The swap test treats a dilemma as a set of comparisons rather than a guide to action, and the dilemma entries give no advice on real decisions.

Related terms

Two other terms are defined on this site: the decoy answer, used in puzzles, and the lone count, used for numbers that have no denominator. The About page explains how dilemma tables label where each judgment comes from.