Should you become a parent? Should you change your career? Decisions such as these change the directions of our lives in irreversible ways. However, it is not just your life that’s changing, it is your self. When making decisions, while facing an unknowable future, we should bear in mind who we are now and who we want to become, writes L. A. Paul.  

Imagine yourself in the following situation: you and your partner are trying to decide whether it’s time to start a family. In particular, you are trying to decide whether you’d like to have a baby. Your financial situation and physical health make the decision to become a parent largely up to what you choose—you have the necessary resources, so it’s about what you want your future lives to be like. This is a paradigmatic “big decision”: the stakes are high, and the choice is irreversible in the sense that, once you’ve had the child, you can’t undo its existence. Even if you give your child up for adoption, you’ve still become a biological parent.

There are many ways to approach a big decision like this, and, if you have any uncertainty about what you’d prefer, you’ll want to think carefully about what you value in order to make the best choice for yourself (and your partner).

Model-based reasoning, where you think about each way you could act, building out the likely consequences of each possible action, and then evaluate and compare these consequences, is the natural way to approach this high-stakes deliberative task. To deliberate, you assess your possibilities to compare them and create (or discover) your preferences. If you can accurately assess the expected value of each act you might perform and compare these values, then when you choose the act that maximizes your expected value, you are choosing rationally.

If you can accurately assess the expected value of each act you might perform and compare these values, then when you choose the act that maximizes your expected value, you are choosing rationally.

The trouble is, for many people, becoming a parent is transformative (Paul 2014, Paul 2015b). because it can transform you both epistemically and personally. If an experience is epistemically transformative, it is an experience that you need to actually undergo in order to know what it is like. If an experience is personally transformative, it changes you in ways that change some of your deepest preferences. A truly transformative experience, like having your first child, is both. When you actually hold your new-born in your arms, you can have an experience like no other, and this can change you in ways that shift some of your deepest preferences.

The shift involves a core value change. Before they become parents, many people prioritize things like their career, financial success, or social achievements. After they become parents, they care more about their child than anything else. Selfishness turns into selflessness. Put more precisely, most of us have a core preference to pursue our own interests, and this preference is replaced with a preference to pursue our child’s interests above our own. This is expressed most keenly by a change in our natural instinct for self-preservation. In a life-threatening situation, while we would want to help others, many of us would save ourselves first, or at least think about saving ourselves first. All of that can change when you have a child. The child (at a level that feels almost instinctual) comes first, even at your own expense. This changes what you care about and how you experience your life. Speaking personally, until becoming a parent, I had never truly understood what it was like to love someone selflessly enough to be willing, without a moment’s hesitation, to sacrifice my life for them. This is just one of the deep and important ways that becoming a parent changed me, and it was a type of change in how I experienced myself and what I value that I was unable to imagine until after I became a mother.

Prospective parents know, before the baby arrives, that a lot is going to change. They can know that they will love their child selflessly, much as I did. And yet, they can’t know how things will change, in the important experiential sense of truly understanding what their new lives will be like with these new values.

Prospective parents can’t know how things will change, in the important experiential sense of truly understanding what their new lives will be like.

The problem is that you can’t (accurately) mentally evolve the world forward in order to imaginatively assess what it would be like for you to have your baby when you live your new life as a parent. Therefore, you cannot compare this subjective value to the value of what it would be like for you to live a child free life. Your subjective value function, which takes as inputs your various possible lived experiences and gives as outputs their respective subjective values, goes undefined at a crucial point. This means that you cannot prospectively assess the value of your future lived experience as a parent.

This creates an epistemic wall between who you are now, and who you’d become as a parent. The epistemic wall is a psychological barrier blocking you from a certain kind of knowledge of your future life. Epistemic walls like these create two serious problems.

The first problem, the problem of undefined subjective value, stems from the epistemic transformation involved. It arises for any theory of rational decision that requires you to assess and compare subjective values in order to maximize your expected utility. If you can’t assign the relevant subjective values of the possible lived experiences, you can’t compare them to rationally decide which life choice is the best one for you.