The famous distinction between formal and material cooperation made by St. Alphonsus Ligouri is difficult to sort out with logical precision, especially in its use of intention and act-indifference, for cases outside the paradigmatic ones and approaching the hazy middle ground of “proximate” material cooperation. A recent book by Fr. Kevin Flannery aims to provide more clarity.
The particular point is that an approach that considers circumstances together with proximity is more useful than one that focuses upon act-indifference. More generally, although the formal/material distinction, especially as understood by Alphonsus, serves some purpose as an approximate way of indicating what cooperation is morally acceptable and what cooperation is not, more sustainable theoretically is the Thomistic approach, which obsesses neither about intention nor indifference.Flannery, Cooperation with Evil, p. 54
That is, St. Alphonsus’s distinction may be a useful confessor’s rule of thumb, but the real fine-tuning of moral analysis requires “Thomistic tools.” Thus far, the book has proved very helpful. More to come, in particular a post (in the works) concerning some current debates about cooperation with evil.