So far, I have yet to see the use of the term "formal cooperation in sin". The quote I gave from McHugh and Callan shows that it is possible to have material cooperation even in matters of idolatry which is much worse than theft.
As for double effect, I thought we already discussed that it is irrelevant after the fact for material cooperation here:
https://www.cathinfo.com/catholic-living-in-the-modern-world/cardinalsbishops-formally-repudiate-2005-vaccine-docs/msg725089/#msg725089
I pointed out the term is not used, but the logic of the argument and conclusion seems to be based on it (“a rose by any other name...”). And the same McHugh-Callan (late 1950’s) manual acknowledges formal cooperation is never permitted (that “never” would include sins less serious than idolatry).
Note also, Fr. Wolfe is not talking about theft alone, but theft predicated upon murder (ie., see my “stealing money from grandma” example earlier in the thread).
As for double effect being irrelevant when having recourse to the direct voluntary, which of the following criteria are you not concerned with:
1) The object be good or indifferent (ie., receiving stolen property obtained by murder);
2) The intention must be good (to knowingly benefit from the double sin is to become an accomplice in it);
3) The good effect cannot come from the bad effect (clear fail: doing evil that good may come by continuous theft);
4) Proportionality: Can I become complicit in murder and theft to keep my job? Or to fly on a plane? If my boss or governor ordered me to desecrate a dead body or grave, I could do it to keep my job?
To get around all this, and contrary to what the old SSPX and Fr. Scott taught, can you tell me why double effect need not be satisfied when deferring to the direct voluntary?
Ps: As regards the late 1950’s McHugh manual, did you know that many moralist, after WWII, began to shift their thinking and morals to focus more on quality of life? I attended a conference with Fr. Is cars (SSPX seminary professor for 25+ years) on end of life issues, where he explained this trend broke out at V2. But if it broke out there, it was certainly present in the minds of some moralists in the 40’s-50’s, which is why I’m suspicious of a manual in 1958. In the words of Fr. Is cars, “If you think I’m going to accept some doctrine just because it has the imprimatur from some American Bishop in the 1930’s, you’re crazy.”
That said, I do not understand your point “after the fact.” Could you refresh my memory?