Been thinking about this for a while: how important is (apparent) teleology in ethics?
Teleology is the study of perceived end-states, or goals, or "functions" of systems in the world. Thus, a teleological system has an end-state, goal, or telos. This telos need not be the product of a silly intelligent-designer, but can merely be a natural, emergent force within certain constraints in which the system inhabits.
I am of the (tentative) belief that teleology does in fact occur in nature, but not in the intelligent design sense. It's just a fact of the world: things have a telos. Functional aspects of a system emerge from habitual processes. It's perfectly compatible with a naturalistic view of the world, especially in biological and cybernetic systems.
What I'm more concerned about here in this post, however, is not the metaphysical status of teleology in nature, but rather the importance teleology may have on ethical decisions. In particular, procreative ethics.
Heidegger famously said that we are beings-towards-death; that is to say, the telos of a human being is death. That's what we're aimed at at the metaphysical level. From the very beginning, we are dying.
The universe itself is "dying". This goes back to a previous post I made on Scarcity and Fatigue.
Now, if the universe was not susceptible to the inevitable entropic heat death, and if humans did not die, then I would likely not have any real issues with birth. For a stable universe would allow a civilization to flourish without end, and the immortality of people would inevitably lead them to a higher-state of being, one filled with bliss, understanding, and peace.
What about suffering? Again, if we did not die, but instead were directed towards a future of eternal bliss, then the suffering would not matter. Nobody would be instrumentalized (since nobody would die and everyone would participate in the blissful future), and everyone would be alright with the suffering that did occur because they would know it would be entirely worth it in the end - for once the blissful end-goal was accomplished, none of the suffering experienced in the past would matter, because it would be gone. The little bit of suffering that one would feel would be entirely worth it, just as the four-years of grueling college is worth it once you start raking in the moneys.
If this seems unreasonably utopian (it is), you have to remember that the reason people feel suffering and are instrumentalized is because other people put their survival before the survival of others. In other words, the ever-present threat of annihilation causes us to put ourselves before others, to create social classes in which the lower classes are systematically exploited, to go to war against each other, etc.
In fact, any non-accidental suffering is directly caused by an avoidance of death. Even more, all pain evolved as a means to keep the organism alive. The lack of resources (Scarcity), and the rather need to avoid death (Fatigue), leads to suffering. Suffering is a direct result of any resource-deprivation.
It stands, then, that any birth results in death.
Why is death bad? Death is bad because it eliminates the ego, and eliminates any possibilities for future enjoyments and dreams. Death is bad for the individual - therefore the avoidance of possible enjoyments by not-procreating is not "bad"(there's nobody there), but the elimination of possible enjoyments by dying is bad, since there's somebody there.
And if death is a good things because it eliminates any possibilities for future sufferings, then this places all blame upon the source - birth. Now, contra Benatar, the avoidance of these sufferings for unborn-people is not "good", however, pace McMahan, the possibility for great suffering (that would make death a good thing), is a bad thing that ought to be avoided. This would constitute a reason for not giving-birth. Therefore, although it is bad to give great suffering upon other people, it's not "good" not to. There's no need to give ourselves a pat-on-the-back for not having children - we're not doing anything good, we're just not doing anything bad, just as me not-murdering-my-neighbor is not good, it's just not bad. Not doing bad does not necessitate doing good, just as not doing good does not necessitate doing bad. And non-existence does not even coherently stand as a state of affairs, let alone a state of affairs that can be of value, thus any claims that Benatar is talking about states of affairs (he's not) fail in virtue of being incoherent.
Attachments are not bad in themselves, they are only bad when they are used inappropriately, i.e. an attachment to a pet that will only live a few years. Unfortunately, any true attachment in life leads to suffering, especially the attachments towards life itself, since life is ultimately transitory and ephemeral, culminating in death.
So in conclusion, death (pace Heidegger) is the final state, the telos of any organism, including the human being, and life is merely a means-to-an-end (to death); that is to say, the very process of life is a process of dying. Any highlights your life may have are entirely transitory and have no relevance on whether or not it was worth being born in the first place, since these highlights are not the telos of your existence, but rather, death is. Everything goes out the windows when you die. The telos of any organism is one in which the organism doesn't even participate in.
And since we should make ethical decisions based upon the final end-state resulting from the decision (including who gets to experience the state and what this state is like), we should not have children because the final end-state is one that either results in a loss of all good, or one that results in the relief of all bad, neither which seem to be good.