The Principle of Double Effect

I think that the meaning of the Principle of Double Effect (PDE) given in the GP notes on euthanasia is vague. So I will try to elucidate the main points in regard to PDE.

According to Wikipedia (I know that the reliability of Wikipedia has been questioned on the premise that it is an open source online encyclopedia, but Wikipedia is in fact considered by many academics to be far superior to the Encyclopedia Britannica), PDE is a set of criteria for evaluating an otherwise well intentioned action which actually has negative 'side effects' at the same time (something like negative externalities in Economics).

Basically, the Principle states that such an action is justifiable if:
1. the nature of the action is itself good, or at least morally neutral;
2. the person intends the good effect and not the bad;
3. the good effect outweighs the bad effect and the person exercises all reasonable diligence to minimise the harm.

Thus, PDE is not merely a simplistic consideration of weighing the pros and cons.

Taking the example given in our notes, we first note that the decision to abort is intended to save Mrs Ong's life, and the death of the foetus is a secondary consequence of this action, which unfortunately cannot be eliminated.

Next, we apply PDE:
1. The decision to abort is out of good intention, because bearing the child would pose a threat to Mrs Ong's life. Thus the nature of the action is itself good.
2. The doctor means well; he advises Mrs Ong to abort to save her life, not to intentionally kill the foetus.
3. In this case, the good effect can be considered to outweigh the harm because if Mrs Ong carried the baby to term, both the lives of the mother and baby would be in danger. If, on the other hand, Mrs Ong chose to abort, she could save her own life.

Since the decision to abort satisfies the three criteria as stated earlier, by Principle of Double Effect, this decision is justifiable.

Hopefully, this post will help to clarify the issue on PDE.