Here’s my defense against both of Tomi’s arguments. Remember, in PAVs, an outcome can only be better or worse if it is better or worse for someone. The utility of adding a person is undefined. It’s not zero. Consider the first problem. We can say that scenario B is better for the 100 existing people. We cannot say that scenario B is better or worse for the ten billion people who do not exist. We therefore cannot say that scenario B is better for the union of these two groups because a positive quantity plus undefined is just undefined. C is, however, better than B for all people together because we are now comparing the same groups.
The same logic applies to the scenario of Adam, Eve and Steve and prevents any issue.
Nice point, but I think it comes at a serious cost.
To see how, consider a different case. In X, ten billion people live awful lives. In Y, those same ten billion people live wonderful lives. Clearly, Y is much better than X.
Now consider instead Y* which is exactly the same as Y except that we also add one extra person, also with a wonderful life. As before, Y* is much better than X for the original ten billion people. If we say that the value of adding the extra person is undefined and that this undefined value renders the value of the whole change from X to Y* undefined, we get the implausible result that Y* is not better than X. Given plausible principles linking betterness and moral requirements, we get the result that we’re permitted to choose X over Y*. That seems very implausible, and so it counts against the claim that adding people results in undefined comparisons.
Here’s my defense against both of Tomi’s arguments. Remember, in PAVs, an outcome can only be better or worse if it is better or worse for someone. The utility of adding a person is undefined. It’s not zero. Consider the first problem. We can say that scenario B is better for the 100 existing people. We cannot say that scenario B is better or worse for the ten billion people who do not exist. We therefore cannot say that scenario B is better for the union of these two groups because a positive quantity plus undefined is just undefined. C is, however, better than B for all people together because we are now comparing the same groups.
The same logic applies to the scenario of Adam, Eve and Steve and prevents any issue.
Nice point, but I think it comes at a serious cost.
To see how, consider a different case. In X, ten billion people live awful lives. In Y, those same ten billion people live wonderful lives. Clearly, Y is much better than X.
Now consider instead Y* which is exactly the same as Y except that we also add one extra person, also with a wonderful life. As before, Y* is much better than X for the original ten billion people. If we say that the value of adding the extra person is undefined and that this undefined value renders the value of the whole change from X to Y* undefined, we get the implausible result that Y* is not better than X. Given plausible principles linking betterness and moral requirements, we get the result that we’re permitted to choose X over Y*. That seems very implausible, and so it counts against the claim that adding people results in undefined comparisons.