It’s the principle of double effect, that’s what!
Sometimes, there’s the desire to produce some good effect; however, if the only way to do that also involves a foreseen but unavoidable and unintended bad effect, there are circumstances in which it’s licit to pursue the good effect.
It’s a pretty nuanced argument, and it requires a number of conditions to be met:
- the desired effect must be morally good (or at least morally neutral)
- the bad effect cannot be intended
- The bad effect cannot be the means by which the good effect is realized
- the good effect cannot be disproportionate to the bad effect
So, in the case of an ectopic pregnancy, the good effect is the preservation of the mother’s life. The bad effect (the death of the baby) cannot be what is intended. One cannot abort the baby (by means of chemicals, for example) as the means by which the mother’s life is saved. (However, if one removes part of the fallopian tube, and this causes the baby to die (but the baby itself isn’t the target of the surgery), then the operation is licit.) Finally, the mother’s life isn’t a disproportionate good as compared to the bad effect of the loss of the baby’s life (if, on the other hand, the baby was killed in order to do something trivial, then the operation wouldn’t be licit).
Keep something in mind: in this analysis, one might be allowed to remove part of the fallopian tube. However, one wouldn’t be allowed to directly kill the baby and remove only the baby (leaving the tube intact); likewise, one couldn’t use abortifacient drugs in order to kill the baby.
One last thing: in this analysis, we wouldn’t call the action an
abortion. The intent would be the preservation of the life of the mother, not the killing of the baby; moreover, the action taken wouldn’t be the direct killing of the baby, but an operation that saves the life of the mother.
So, in a very real way, the answer is ‘no’ – there wouldn’t be sufficient cause to say “go ahead and abort the baby”; however, there might be sufficient cause to perform an operation that would foreseeably (but unintentionally) result in the death of the baby.