Introduction - What is antinatalism?
The basic premise of antinatalism is that life contains more suffering than we think, and therefore, since there's a strong chance or certainty of suffering, bringing someone to life (or any sentient being) is immoral since it almost always or always involves imposing suffering on a sentient being which did not request to be born. IE not coming to live entails not suffering, however coming to live, even if there are joys, involves suffering. Hence, Benatar and his ilk argue, it is immoral to birth a child since you are bringing a being into existence who "better would not have been", since they will no doubt suffer.
Pronatalism
I reject this view and hold the view of pro-natalism, that is, that we ought to create more life. It is one of the few things I agree with Musk about. Here's the counter or pronatalist position.
1. Moral value inheres in sentient beings.
2. Moral value, according to Bentham and other utilitarians, can be calculated additively. So for example, the suffering of 10 people is worse than the suffering of 1, and vice versa, the benefit of 10 people is better than the benefit of one. Obviously, not all sufferings are equivalent, so we can't for example dissect someone to use their organs to rescue 10 people, since the suffering and trauma of that one person, so dissected, is worse than the natural deaths of the 10. Unless of course the person volunteers, and is anaethetised, etc. I can imagine a scenario like that, e.g. were I to offer my organs to say my children, and therefore think that even this extreme case is not convincing.
3. If moral value is additive, more sentient beings equates to more moral value inherently existing in the universe.
4. Therefore, if there are more morally valuable beings in the universe, this equates to a morally better or preferable universe.
Why Buddhism is unethical
Buddhism claims that suffering is inherent in the universe. That is true to a certain extent. As I have argued in a paper on evolution, evolution requires death, and therefore humans would not have evolved without unfit humans and/or their predecessor hominins having died. However, let's not forget that Siddharta Gautama (Buddha) was a prince, and therefore had LESS suffering than the other citizens in his primarily Hindu Caste-based society that he presided over as a prince.
In fact, my problem with him is that like the Dalai Lama, he was happy to maintain an elitist system and do nothing with his princely power to eliminate suffering. He just figured it was inherent and therefore that you should just be an ascetic and deny yourself pleasures etc., and meditate. No thanks. That's just pseudo-enlightened nihilism, in my view, aka, shrugging at those less fortunate than yourself and saying "the poor will always be with us". No not true. Jesus was wrong on that one too. Buddhism is a conservative view which entails not righting wrongs or injustices in society because "suffering is inherent." No it's not.
Where does suffering come from?
I think it's clear that in our current era, most suffering relates to capitalism and male-originating violence such as gun violence and GBV, and/or other social problems such as poverty, inequality and racism. Those who live in upper-class wealthy english-speaking households have minimal suffering. At most, they might have things like domestic disputes, or drug abuse problems, etc., but it is unlikely that they have other forms of suffering which are more than mere first world problems. Their wifi perhaps goes down and perhaps the maid doesn't arrive to clean. Perhaps they get a flat tyre on the road, or their car gets stolen. But I seriously doubt there is significant suffering if you are socioeconomically prosperous. Therefore, I believe that at present, most suffering is manmade and specifically a byproduct of capitalism and inequality (as well as racism, sexism, etc).
Of course, suffering exists in nature. For example, the trauma that a penguin experiences when being ripped in half by an leopard seal is probably much greater than most trauma that most humans experience (except perhaps those who witness their family die in a car crash, or those who are subjected to colonist racist invasion of their territory and subsequent attempts at genocide). However, humans in general no longer live in a "state of nature", as Hobbes points out, because we decided that life in a state of nature was "nasty, brutish, and short", and that nature was "red in tooth and claw", as Hobbes put it. So we invented laws and society to inhibit natural violence.
To refute this you would have to show that (a) horror is inherent in the universe and (b) that horror outweighs joy. I do not think this is true, as I think horror is mostly manmade. But even if we take the combined horror of World War 2, The Congo, Rwanda, The Long March, Pol Pot, the 2004 Tsunami, etc., we still only get to about 110-120 million horrific deaths; whereas we have almost or about 8 billion people now - so horror, as far as I can see, represents about 1.25% of humanity's existence.
We can also reject antinatalism's claim - that horror outweighs joy - qualitatively and by measure of concentration. Let's say your life is mostly full of joy, you never experience anyone's death, and right at the end after 80 years, say, you die in a car accident and watch your broken body bleed out. That I think is probably the most horrible way to die that commonly happens on earth (more horrific deaths, such as by torture, are extremely rare). However, your death will take a mere matter of minutes, which does not at all outweigh the joyous life you had had. The quality and quantity of that horror - your brutal death - is a matter of a few intense minutes. This horror, in my view, is outweighed by just a few nights with a lover. And you probably had many thousands of such nights.
From this I conclude that horror does not outweigh joy, and that horror is mostly manmade. If we implement a true form of communism/socialism, such as we see proposed in the Venus Project, there will be no significant suffering that exceeds the joys of being alive. Personally, if I were a spirit in the Realm of the Forms or Heaven or Nirvana or whatever your myth is, and I were shown my life, and asked whether I wanted to be born, knowing what my life would be like, I can say certainly I would, as my life has had minimal suffering. The worst suffering I experienced thus far was my first romantic breakup; the second worst was the death of my father. However, both have been outweighed by far by my children's birth, and subsequent relationships which have cumulatively outweighed these hurts.
In my view, a universe without living beings is a worthless, pointless universe, that may as well not exist. A universe with some suffering and a lot of joy is preferable to a neutral universe with no suffering and no joy, from a God's-eye-view. On this point I agree with the Christians: that a universe capable of life is the sort of universe a God would make (one with a purpose: sustaining life).
Conclusion
The value and joy of being alive is primarily in the value and joy of relationships with others. Hence, it is imperative that others exist for joy and moral goodness to exist. Meaning in life only comes from others. Sartre said "L'autre c'est L'inferne" (other people are hell). I disagree. I think hermetic life, or nihilism, are hell. And I think antinatalism is a form of extreme nihilistic atheism.
Life has good and bad in it, but mostly good, and that's why people manage to carry on living every day, even when suffering due to violence, poverty and racism. If you find life is overwhelmingly suffering, I wager you are either very socioeconomically disadvantaged - in which case I suggest you join your local chapter or branch of a socialist or communist movement - OR you suffer from depression, in which case I suggest you get psychiatric help, or agitate for free psychiatric help in your country.
good summary video on the issue: https://www.youtube.com/watch?v=F0YxEa1AG4M&t=19s