[Question:]{.underline} Is it permissible for a landlord to rent out an apartment or house to an unmarried couple living in sin?
[Answer:]{.underline} This is a case of material cooperation in somebody else’s sin. This is not normally permissible, for obvious reasons, and a Catholic ought to refuse to rent an apartment if he knows that a couple is not married and is going to live in sin in that apartment.
However, material cooperation is not the same as formal cooperation. The difference is that in material cooperation the Catholic (in this case, the landlord) does not want the sin to happen, whereas in formal cooperation he does. This is why it is permissible to rent to such persons for a proportionately serious reason; for example, if the civil law made it an offense to “discriminate,” and one did not have any other “legal” reason to refuse, so that the refusal to rent would mean a real possibility of civil or criminal action being initiated against the landlord.
This being said, a Catholic should do everything in his power, including accepting a lower rent from good tenants, or using other legally approved reasons to exclude such tenants, in order to avoid even material cooperation in such a sin. However, if a Catholic were trying to do this, but got caught, and was afraid of being sued, then he could rent it to such a couple, as effectively having no choice. Here the principles of the indirect voluntary apply. What is directly willed is not the cooperation in another’s sin, but the gaining of a just return for his investment.
This very real possibility ought not to dissuade Catholics from owning rental properties. For to do so is to provide a service for the poor, underprivileged members of society less able to take care of themselves. Understood in this sense it is an act of charity, especially when the landlord is willing to give the needy a break on their monthly rent.
Answered by Father Peter Scott, SSPX.