As for your first question about the philosophical implications of this psychological research: In general, the primary goal of our project was a descriptive one and it would require a separate project (ideally lead by philosophers) to figure out what the possible normative implications are. I also believe that we need much more empirical research to understand in greater detail what exactly the psychological mechanisms are that drive people’s population ethical views. I see this as a very first exploration.
That said, I agree with much of what Jack says in the other comment. We should be cautious in simply accepting lay people’s intuitive reactions to these tricky moral dilemmas or even making our policies based on them. Most people’s reactions are very uninformed (most have never thought about these questions before), their reactions are often inconsistent, framing-dependent and — as we saw in some of our studies — people themselves tend to revise their opinions after more careful reasoning.
At the end of our paper, we say:
However, this [the fact that people’s judgments are inconsistent and biased] does not mean that it is not valuable to examine lay people’s population ethical intuitions. Population ethics has important implications for policy making and global priority setting. Philosophers often rely on their own intuitions when discussing population ethics. An understanding of the psychology of these population ethical intuitions can therefore be informative. For example, greater awareness of the specific psychological mechanisms and biases driving these intuitions could elucidate which ones should be endorsed under reflection and which ones not. The apparent inconsistencies between some of these intuitions demonstrate that it may be impossible to formulate a population ethical theory that is both consistent and intuitive (cf. impossibility theorems; Arrhenius, 2000). One possible solution could be a debunking approach: attempting to understand the psychological underpinnings of different philosophical positions, with an eye to identifying those that result from unreliable or biased cognitive processes. This in turn allows the resolution of inconsistency by discounting certain intuitions as untrustworthy (cf. Greene, 2014). Another possible resolution is to accept the fact that we are internally conflicted and, as a consequence, uncertain which moral theory is right (MacAskill, Bykvist, & Ord, 2020).
As for your second question about the adding-people experiment (Studies 2a-b): You are right that participants may misinterpret our dilemmas and questions. This is a general issue with studying such abstract questions and we tried our best to make things as clear as possible to people. In most studies, for example, we double checked if people understood and accepted our assumptions (and excluded participants from the analyses who have failed these checks).
In Studies 2a-b, the question we asked was “In terms of its overall value, how much better or worse would this world (containing this additional person) be compared to before?” (1 Much worse − 7 Much better). Even though this seems pretty clear to me, I think you’re right that it’s possible that some participants also considered the indirect effects on other people it would have to add a new person. One reason why I believe our finding would largely stay the same, even if we ensured that participants did not take the indirect effects into account, is the empty world condition in Study 2b. (And this relates to your comment.) In Study 2b, we indeed had a condition where the initial world contained zero people (empty world) and another condition where the initial world contained 10 billion people (full world). And even in the empty world condition, where you’d expect such indirect-effect considerations to be ruled out, we still find the same pattern. (That being said, I believe it’s possible that a different question and different framing could yield different results.)
Regarding your comment, let me clarify: in Study 2a, the initial world contained 1 million people, but in Study 2b we tried to replicate this effect with a scenario where the initial world contained either zero people or 10 billion people. I believe this should be described correctly in the paper (if not, please let me know). But I noticed that there was an incorrect paragraph in our supplementary materials, which may have lead to this confusion and which I’ve now fixed (Thanks for making me aware of it!).
Thanks, these are great points!
As for your first question about the philosophical implications of this psychological research: In general, the primary goal of our project was a descriptive one and it would require a separate project (ideally lead by philosophers) to figure out what the possible normative implications are. I also believe that we need much more empirical research to understand in greater detail what exactly the psychological mechanisms are that drive people’s population ethical views. I see this as a very first exploration.
That said, I agree with much of what Jack says in the other comment. We should be cautious in simply accepting lay people’s intuitive reactions to these tricky moral dilemmas or even making our policies based on them. Most people’s reactions are very uninformed (most have never thought about these questions before), their reactions are often inconsistent, framing-dependent and — as we saw in some of our studies — people themselves tend to revise their opinions after more careful reasoning.
At the end of our paper, we say:
As for your second question about the adding-people experiment (Studies 2a-b): You are right that participants may misinterpret our dilemmas and questions. This is a general issue with studying such abstract questions and we tried our best to make things as clear as possible to people. In most studies, for example, we double checked if people understood and accepted our assumptions (and excluded participants from the analyses who have failed these checks).
In Studies 2a-b, the question we asked was “In terms of its overall value, how much better or worse would this world (containing this additional person) be compared to before?” (1 Much worse − 7 Much better). Even though this seems pretty clear to me, I think you’re right that it’s possible that some participants also considered the indirect effects on other people it would have to add a new person. One reason why I believe our finding would largely stay the same, even if we ensured that participants did not take the indirect effects into account, is the empty world condition in Study 2b. (And this relates to your comment.) In Study 2b, we indeed had a condition where the initial world contained zero people (empty world) and another condition where the initial world contained 10 billion people (full world). And even in the empty world condition, where you’d expect such indirect-effect considerations to be ruled out, we still find the same pattern. (That being said, I believe it’s possible that a different question and different framing could yield different results.)
Regarding your comment, let me clarify: in Study 2a, the initial world contained 1 million people, but in Study 2b we tried to replicate this effect with a scenario where the initial world contained either zero people or 10 billion people. I believe this should be described correctly in the paper (if not, please let me know). But I noticed that there was an incorrect paragraph in our supplementary materials, which may have lead to this confusion and which I’ve now fixed (Thanks for making me aware of it!).
Thanks for this answer! It was really helpful. I hadn’t spotted that the ‘empty world’ really was empty in the experiment; not sure how I missed that.