A startling and honestly distressing view is beginning to receive serious consideration in both academic and popular discussions of climate change ethics. According to this view, having a child is a major contributor to climate change. The logical takeaway here is that everyone on Earth ought to consider having fewer children.

Although culturally controversial, the scientific half of this position is fairly well-established. Several years ago, scientists showed that having a child, especially for the world’s wealthy, is one of the worst things you can do for the environment. That data was recycled this past summer in a paper showing that none of the activities most likely to reduce individuals’ carbon footprints are widely discussed.

The second, moral aspect of the view — that perhaps we ought to have fewer children — is also being taken seriously in many circles. Indeed, I have written widely on the topic myself.

But scientific evidence and moral theorizing aside, this is a complicated question with plenty of opponents. In what follows, I will address some of the challenges to this idea. Because while I recognize that this is an uncomfortable discussion, I believe that the seriousness of climate change justifies uncomfortable conversations. In this case, that means that we need to stop pretending the decision to have children doesn't have environmental and ethical consequences.

The argument that having a child adds to one’s carbon footprint depends on the view that each of us has a personal carbon ledger for which we are responsible. Furthermore, some amount of an offspring’s emissions count towards the parents’ ledger.

The seriousness of climate change justifies uncomfortable conversations. Matt Nighswander / NBC News

Most environmentalists accept this sort of ledger view when it comes to recycling, driving, and flying, but support begins to decrease when applied to family planning. The opposition is typified by Vox writer David Roberts, who argues that “such an accounting scheme is utterly impractical” because it seems to entail that one is never responsible for one's own emissions. Because "we don’t want to double-count,” as Roberts says, this means parents are really only responsible for their kids’ emissions.

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The flaw in this objection is the plausible-sounding caveat: “we don’t want to double-count.” Because why wouldn’t we want to double-count? If moral responsibility added up mathematically, then double-counting would be a serious problem. But I think it’s clear that we should not accept a mathematical model of responsibility.

Consider a different case: If I release a murderer from prison, knowing full well that he intends to kill innocent people, then I bear some responsibility for those deaths — even though the killer is also fully responsible. My having released him doesn’t make him less responsible (he did it!). But his doing it doesn’t eliminate my responsibility either.

Something similar is true, I think, when it comes to having children: Once my daughter is an autonomous agent, she will be responsible for her emissions. But that doesn’t negate my responsibility. Moral responsibility simply isn’t mathematical.

If you buy this view of responsibility, you might eventually admit that having many children is wrong, or at least morally suspect, for standard environmental reasons: Having a child imposes high emissions on the world, while the parents get the benefit. So like with any high-cost luxury, we should limit our indulgence.