Comment: A bartender for example has the obligation not to serve a customer he views as inebriated. If he continues to serve that person, he could be legally liable for the collateral damage that inebriated person does. That’s not only true legally in our system of laws, but also a religious truth
This is at least theologically certain and seems to be proximate to faith as it is ascertained by various passages in Sacred Scripture. Cf. 2 Jn. 1:11, Prov. 22:24 etc.
This is strictly of faith, as defined by the First Vatican Council (1869-1870):
If anyone says that divine revelation cannot be made credible by external signs, and that therefore men and women ought to be moved to faith only by each one’s internal experience or private inspiration: let him be anathema.
The principal of double effect is not anything particularly fundamental. It it really a tool to help in the interpretation of the the 3 fonts of morality. [It is often poorly expressed too.]
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