The Doctrine of Double Effect

The aim of the article is to present some of the differences and similari- ties in various versions of the double effect principle (DDE or PDE). The following formulations will be analyzed: that of Thomas Aquinas and two contemporary ap- proaches, namely those of Mangan and Boyle. It will be shown that the presented modern versions vary significantly and the distinction between their intended and only predicted effects is far from clear. As a result, the different contemporary for- mulations of DDE lead to contradictory conclusions, with some justifying what the others condemn. Moreover, it will be demonstrated that, unlike Aquinas, contem- porary authors mostly concentrate on unintentionality condition while neglecting the proportionality requirement. So, unlike Aquinas, they only take into account a narrow scope of cases, where the evil effect occurs with certainty, which leads to a complicated and intricate hypothetical intention test like Donagan’s. It will be shown that, besides its theoretical indistinctness, DDE lead to serious pragmatic risks. It can be quite easily misused as a kind of psychological mechanism to protect self-esteem from a sense of guilt since wrong-doing is treated as merely a predicted unintended effect.