When is it permissible to procreate? Is it right for an unmarried person to seek to have a child, or to engage in actions that are likely to result in procreation? Is it right for an infertile couple to seek to conceive a child with the help of donor sperm or eggs? Should those who are poor or who live in a war-torn society avoid having children? What about those who are likely to pass on a serious genetic illness?

Rivka Weinberg seeks principled answers to these and other ethical questions regarding procreation in her new book, The Risk of a Lifetime: How, When, and Why Procreation May Be Permissible.

As the title indicates, Weinberg sees life not as a gift but as a risk, and believes that imposing that risk on someone requires justification. The core thesis of the book is that the moral acceptability of any procreative act “depends on the nature of the risk, the likelihood of its ripening into harms or benefits, and the interests people have in imposing it.” In other words, determining the moral permissibility of procreative acts involves balancing the interests of would-be parents against the interests of future children. Weinberg also argues that those engaging in procreative actions must have the right motivations.

The question of proper motivation is examined in Chapter One. Weinberg points out that one’s motivation for procreation itself cannot be the good of the child. Prior to his or her existing, there is no subject who needs or wants existence. A second option—procreating for the sake of “adding value to the world”—seems too impersonal, and it instrumentalizes the future person. After addressing several other possibilities and conundrums, Weinberg concludes that “the desire to engage in the parent-child relationship as a parent” is a motive for procreating that both accords well with experience and respects the future child, given that, once the child exists, receiving parental love and care will be beneficial to the child.

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Chapter Two examines the question of who counts as a parent—in other words, how one comes to acquire parental responsibility. Against those who claim that parental responsibility is triggered by causing a child’s existence, intending to raise a child, gestating a child, or being a genetic parent, Weinberg develops a “Hazmat Theory” of parental responsibility. She claims that, like explosives or pet lions, our gametes are potentially hazardous materials that we must handle with extreme care. Thus, “if we do things that put our gametes at high risk of joining with others and growing into persons, we assume the costs (and rewards) of that risky activity.” Hence, we incur parental responsibility for the resulting children.

Weinberg also argues that, since love is one of a child’s basic needs and the duty to love cannot be transferred, parental responsibility cannot be transferred—a view that I have also defended in a number of articles and in my book on parental rights. Weinberg recognizes that this view implies that gamete donation is a failure of parental responsibility and is therefore morally wrong. To her credit, she does not try to wriggle her way out of this unpopular, procreative-liberty-restricting conclusion. Rather, she defends it unapologetically.

Still, it seems to me that Weinberg’s dismissal of genetic accounts of parental responsibility (and thus of the inherent significance of the genetic parent-child bond) undermines her argument. As I have already argued in a previous article, one can only fully explain why a gamete donor may not transfer his parental responsibilities to competent others by acknowledging that children have a permanent and identity-defining link to their genetic parents that makes the love of those parents non-substitutable. Others, of course, can love those children deeply, but once children learn that the parents raising them are not their genetic parents, they can (as donor-conceived and adopted children often do) miss the specific love of those whose genetic contribution made them who they are at the biological level, and who may therefore offer them important insights into their personality traits, interests, physical characteristics, susceptibility to particular illnesses, etc.

In Chapters Three and Four, Weinberg makes the case that procreation is neither almost always right, nor almost always wrong. The non-identity problem—the fact that waiting to have a child until conditions are more favorable simply means that you will have a different child—may seem to imply that procreation is always or almost always permissible, since the person brought into existence in terrible circumstances would otherwise not exist at all. Weinberg skillfully resists this conclusion, in part by arguing that for many ethical theories—for instance, consequentialism (which holds that the morality of an act is determined solely by its consequences), and theories that focus on how an act affects the moral character of the agent—the non-identity problem is irrelevant. While it seems to me that her resistance ultimately rests on some (very impressive) rhetorical sleight of hand, her arguments are worth grappling with.

Finally, in Chapters Five and Six, Weinberg proposes two principles of procreative permissibility, and applies them to real life cases. Those principles are: (1) The Motivation Restriction, which is based on her argument in Chapter One, and (2) Procreative Balance: “Procreation is permissible when the risk you impose as a procreator on your own children would not be irrational for you to accept as a condition of your own birth (assuming that you will exist) in exchange for the permission to procreate under these risk conditions.” She defends the Procreative Balance principle from a Rawlsian perspective, but also believes that it is intuitively plausible even apart from the Rawlsian framework.

The application of these principles leads to some sensible conclusions, but ultimately the principles seem both under-restrictive and over-restrictive, depending on the case. For instance, Weinberg recommends (almost apologetically) that people should marry prior to having children, given the well-established risks of single parenthood for children’s well-being. Yet she hedges this claim by arguing that in some cases the procreative liberty of the would-be single parent may outweigh the additional risk to the child. Unsurprisingly, she also ignores the data indicating that children raised by same-sex couples (even by married same-sex couples) are at significantly greater risk of mental health problems, sexual abuse, and a host of other negative outcomes than those raised by their own married biological parents.

One instance in which Weinberg’s principles seem overly restrictive is their application to the number of children one may permissibly have. The unique benefits of experiencing the parent-child relationship as a parent diminish sharply, thinks Weinberg, after one’s first child. Weinberg seems to allow that having a relatively large family could be permissible (presumably in relatively ideal circumstances with healthy, married parents in a good socioeconomic situation), but with each additional child the permissibility of procreation becomes increasingly suspect. She argues, for instance, that if one’s children have a 1 percent chance of suffering from schizophrenia, the benefit of procreative liberty could justify having one child, but most certainly not five. (The exact cut-off point is unclear.) Likewise, it may be permissible for those who are poor to have one or two children, given the great potential benefit to the would-be parents, but more than that would be difficult to justify. Weinberg also claims that procreation is most likely not permissible at all if one’s child is likely to have a significant cognitive disability.

Perhaps many will find these restrictions quite sensible (especially since they are proposed only as moral guidelines, not as restrictions that ought to be legally enforced). Yet they fail to take into account that there may be more at stake for would-be parents than the possibility of enjoying the unique benefits of the parent-child relationship.

Procreation is not a good that should be sought in isolation, but rather should be sought as a natural fulfillment of one’s marital union. In choosing to engage in sexual intercourse, one should be choosing to seal, actualize, and express one’s marital union, a union not only of minds and hearts, but also of bodies. This bodily union is constituted by the joint coordination of male and female toward the shared biological end of reproduction. Thus marital love, while not always resulting in procreation, is inherently ordered to and fulfilled by procreation.

It is fairly clear that Weinberg would reject the above view of marriage (defended here in greater detail). Nonetheless, Weinberg is concerned throughout the book to defend an understanding of the reasons for procreation that is in line with common human experience. And in common human experience, getting married and having children are two things that go hand in hand. Even in our post-sexual revolution society in which contraceptive use is widespread, many (if not most) still presume that an important and distinctive part of married life is having and raising children together (at least at some point).

While it is understandable that Weinberg would want to sidestep these issues, discussing procreative ethics in a way that is completely disconnected from sexual ethics or marital norms seems strange —kind of like discussing military ethics without mentioning anything about the conditions for a just war.  Discussing these issues in isolation from each other is certainly not impossible or inherently incoherent, and it may have some advantages. But the reader is left wondering how different the conclusions might be if this key piece of the puzzle had been included in the analysis.

Overall, Weinberg’s book is an insightful and lively discussion of a difficult and sensitive topic. I disagree with many of Weinberg’s presuppositions—including her view of life as a risk rather than a gift, and her presumption that (even within marriage) avoiding procreation should be the default, while openness to procreation requires special justification. Nonetheless, given the growing prominence of such presuppositions, exploring their implications for procreative ethics is worthwhile. Even those skeptical of Weinberg’s approach will find much food for thought in her work.