Accessory to Another Person's Sin - Mortal?


Theoretical question. I am familiar with the nine ways to be an accessory to another person’s sin. However, I do have a question about the gravity of being an accessory. Does the gravity of being an accessory depend on the gravity of the primary sin committed, on the way one participates, or a combination thereof? I would imagine that ordering a person to commit murder is obviously a mortal sin if the murder is committed, but let’s say that a girl loses her virginity to the starting quarterback and his friends praise him for his “exploits.” Or her friends try to defend her by saying that the quarterback seduced her. The primary sin would be fornication which is definitely mortal. The accessory sins would be praise or flattery on one side, and defense of the wrong done on the other. Would the boy’s friends be guilty of a mortal sin? Would the girl’s friends be guilty of a mortal sin?


The gravity of any sin at all depends on three things:

  1. your intention – the greater the disorder in the intention, the graver the sin.
  2. the moral nature of the chosen act (determined by its object) – the greater the disorder in the object(s) of the act, the greater the sin.
  3. the circumstances – here the reasonably anticipated good and bad consequences of the act are weighed; the more that the bad outweighs the good, the greater the sin.

For cooperative acts, the same basic criteria above still apply.


If you are an accessory to a mortal sin of another, then you have committed a mortal sin; the degree of support doesn’t matter in this regard (supporting a mortal sin only a tinsy bit is still a mortal sin). I would say that both the girl’s and the boy’s friends would have committed mortal sin. Also, if someone were to command another to commit murder, that would be a mortal sin regardless of whether the person chooses to murder or not.


It depends on several factors. The action, the intention, and the consequences.

There is formal material cooperation, immediate material cooperation, mediate material cooperation, remote material cooperation, and complicity. Each carry a different degree of culpability.


In cases where the person didn’t know a mortal sin was being committed, I think culpability is very little, if any.

For example, if one works in a factory that manufactures instruments that open a woman’s cervix for routine gynecological and obstetrical care, yet some are sold to abortion clinics and used in abortions, the manufacturing workers, providing they do not approve of abortion, would not be culpable.

A nurse who operates the vacuum machine in an abortionist’s clinic, however, would be committing a mortal sin just as the abortionist would.

A pharmacist who fills a prescription for an abortifacient would be guilty of mediate material cooperation, providing he does not approve of abortion.

It gets complicated. LOL (I do know it’s no laughing matter.)


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