Eric has recently attention to this wonderful paper by L.A. Paul. The paper focuses on the question of how we make decisions that can transform our lives, and whether we can ever do so rationally. Her paper looks at the decision whether or not to have children, but it applies to other potentially life-transforming decisions, such as whether or not to go to graduate school or get involved romantically with someone.
Here, I don't want to focus on Paul's claims about the extent to which we have knowledge about what's it like to be a parent. I think, like Eric, this depends a lot on cultural context, and westerners seem to be in a particularly impoverished epistemic position because of the rarity of children, and the cultural ideals that surround it. Parenthood is described in unrealistic romantic, language (e.g., when I was pregnant, friends and family assured me that I would be in a blissful and rosy cloud like state after the birth of my child; breastfeeding would be easy and a wonderful way to connect to my baby; I would forget the pain of childbirth the moment I held her in my arms - all claims that turned out, at least for me, false and made me wonder if anything was wrong with me).
But I think that Paul is nevertheless right that decision theory does not provide us with the right tools to make potentially life-transforming decisions. When westerners today have children, Paul observes that there is a cultural ideal to "think carefully and clearly about what they want before deciding that they want to start a family." How do we do this? According to standard decision theory "we first partition the logical space by determining the possible states that are the outcomes of each act we might perform. After we have the space of possible outcomes, we assign each outcome a value (or utility), and determine the probability of each outcome’s occurring, given the performance of the act." However, she goes on arguing, convincingly, that this model fails, as it is impossible to calculate expected value based on preferences about what it would be like to have one's own child.
Drawing on Jackson's Mary's Room thought experiment, she argues that we don't know what it will be like for us, as individuals, to be a parent. As potential parents, we are in an empoverished epistemic position like Mary prior to leaving her black-and-white room. Things don't improve when we use other models of decision theory that start from an assumption of ignorance. Also, as Paul observes, objective chances (frequency probabilities) don't help either. Sociological studies comparing childfree people with people with children indicate that most people do not increase their overall utility by having children, measured in terms of life satisfaction, happiness etc. So relying on objective chance is a bad strategy. It is similarly a bad strategy for other life-transforming decisions, e.g., going to graduate school or getting married. Indeed, if objective chance were a good criterion for such decisions, they would simply be irrational.
Perhaps we need to abandon decision theory and other utility-based models as models for decisions that are potentially life-transforming. In the Will to believe, William James has argued that it is rational to have religious belief without evidence in certain circumstances, for instance, when evidence only becomes available once one believes, or in the case of self-fulfilling beliefs - beliefs that make themselves true.
When we examine the domain of practical rationality, and the question whether or not to have children, some of these considerations apply. Suppose Paul is right (as I think she is) that we only gain what's it like type evidence of being a parent after becoming parents. Then we cannot use this evidence to become parents, but becoming a parent is an important condition for getting the evidence. I'm not saying that a desire for this evidence this is a sufficient or rational reason for becoming a parent. But at least it seems to make sense of the desire, expressed my many prospective parents, of becoming a parent. They know it will transform their lives, emotions, and relationships with others, and they want to experience this.
Similarly, some people believe that being a parent is important to them to having a fulfilling life. I do not subscribe to this - many people are childfree and lead happy and fulfilling lives. But some years ago, I read a book with testimonies by people who were involuntarily childless (I do not recall the title or author) - and it struck me how many of the interviewed people, men and women, were mourning the loss of the children they never had. They sincerely believed children were an important condition to make their lives, as individuals, or couples, complete, and it seems that this belief was self-fulfilling, i.e., they definitely felt they were missing out on something. There are of course cultural factors involved here, but whatever its origin, if one believes this to be the case, it may become true by virtue of the belief.
So given these two factors - a desire for the experience of being a parent, even though we don't know what it's like or whether it will increase utility, and a belief that being a parent is important for our overall life goals - seem to make it rational in a Jamesian picture for people to choose parenthood, even if they are in the extremely impoverished epistemic situation that Westerners today are in when faced with that choice.