Procreation and Morality
Given that serious harm in life is practically inevitable, is it better to have lived than not to have existed at all? David Benatar makes a strong case in favor of non-existence, particularly when it comes to the issue of procreation. He believes that the morally responsible thing to do is not to procreate, because "the only way to prevent harm altogether is to desist from bringing children into existence". Here is a summary of Benatar's position in his own words.
As anticipated by Benatar, my immediate impulse is to argue that there is significant good in life that justifies existence even if it doesn't outweigh the harms, but on reflection I recognize that to believe (baring exceptions) that it is better to be alive than not is essentially a value-judgement, and it is a value-judgement that springs not from pure rational considerations but rather from the brute, biological will to live.
There is another way to frame this question aside from the context of procreation. The ability to create life puts us in a miniature God-like position. Now imagine God pondering over the decision to create this universe (more specifically, the decision to create sentient beings capable of subjective experience). The same considerations of harm vs good in existence present themselves but on a much grander scale, applying to the whole of creation. Is it better to bring into existence beings who would experience the excruciating horrors of this world, even though at times they would have their share of bliss as well? If God did create this universe, then God made the value-judgement of preferring life over non-existence. From Benatar's perspective, this decision was morally irresponsible on God's part. He should've let non-existence be.
This is not a mere philosophical problem of no consequence. The decision to have or not have kids is a decision that the vast majority of humanity has to make at some point during their lives. Most of us decide either thoughtlessly or selfishly, but few pause to wonder what is the better outcome for our potential children. Are they better off alive or notional? We don't know, and we have no way of knowing, and yet we have to take that decision anyway.