I do not understand this. Is the argument that people experience happiness when alive and it is a good thing, so we should procreate? If so, it is as good as the argument that existence has harm and we should steer away from harm at all costs, so we should not procreate-not that good.
Also, why should we adopt the non-agression principle? I believe that the answer to this question can help us understand whetever reasons for procreating justify violating it are good or not. — HereToDisscuss
So we have two ideas here: non-aggression principle, pursuit of happiness.
In this variation of it, I would identify non-aggression as not imposing one's views on others through force. I'd like to acknowledge and then set aside the idea that in this view, self-defense and preventative defense is justifiable as it is defending against an initial force or threat-to-force.
It can also be argued that having children is a forced outcome. The parent views that another being should be born and experience the world because they feel it is good or necessary, and thus they procreate (this is "forcing" the child). Let us also acknowledge that the "force" is making the events possible for the person to be born. Thus, even though there is no actual person existing before X time, at some X time, when the child exists, it is indeed brought about through the actions of the parents, which is where the "force" has taken place. Thus any arguments saying there was no child before X time to be forced are specious and red-herring arguments, as the X time when the child actually exists IS the time when force has taken place. Nothing more or less is needed there to demonstrate that.
When interviewing parents as to possible reasons for having kids (outside accidental births), inevitably a pattern emerges whereby some idea of "happiness" or "flourishing" emerges (maybe not said in exactly those terms, but amounts to similar concept).
Thus the parent may indeed go about life believing in the non-aggression principle in regards to property, physical autonomy, and freedom of speech. However, in the case or procreation, this is never linked as also following under this purview of non-aggression. Birth is seen as an exception to non-aggression (i.e. not forcing physically or otherwise) on someone. Further, if this was ever presented as just another case of aggression and force onto someone, they wold make the pivot to some version of the happiness principle. People "need" to be born to pursue their happiness. This overrides (is a post facto-excuse) any non-aggression principle that they may otherwise have. Thus the pursuit of happiness idea acts as sort of way to dissolve the tricky problem of aggressively forcing (literally everything about life) onto another person.
So, why should we adapt the non-aggression principle? Why should people be forced into anything at all? That is the heart of the matter. There is an agenda taking place, and this agenda is literally forced onto the next generation. Why should the person be forced into this agenda, be it happiness principle or otherwise? Let me ask you this, if happiness is the goal, are parents then messianic "deliverers" of happiness by having children? Are they on some sort of mission whereby individuals are beholden to follow? This may sound odd, but that is the logical conclusion of such thinking- even if the person presenting it has not thought it all the way through.