Thanks for the post. You raise some interesting issues but ultimately the diagnosis and solution to the problem seems flawed and misguided to me. It seems as though you’ve anticipated some of these counter-arguments yourself.
To begin with, I agree that thoroughgoing utilitarianism may lead to conclusions that most of us, including those in the EA community and believers in that ethical system, would not find palatable for variety of reasons one of which being that militates so strongly against common sense. In that scenario of course, one could modify certain tenets of the ethical theory (for example, there are variants such as negative and rule-based utilitarianism which may be more suitable) or one can accept that one is unwilling to follow through because of one’s own limitation. The latter could take the form of strong social conditioning, the fact that we ultimately live in a human society and largely abide by the common moral assumptions or that violates something that is important to us, etc. In all cases though, we recognize that it is our limitation. On the other hand, your prescription in these situations is to use common sense as the guiding ethical principle. The problem, as you seem to have already recognized, is that this brings in a tremendous amount of arbitrariness into the decision framework. And if we take that to its logical extreme, then one can justify eating meat because common sense dictates that doing so is normal and ubiquitous. Double down on the justification meat-eaters claim such as the values of sharing food with family and community, cultural significance, sense of belonging etc.
I am generally in agreement with the incommensurability of values in several situations but the resolution of that cannot be merely practical wisdom. At least not in theory. We need something else and I agree that in the interim, that may be relative weights that are unappealing in their own right, but that is still better than resorting to common sense/practical wisdom. Just to be clear, in practice, I fully understand if someone prefers to donate to save 10 human lives versus improve the welfare of 10 million fish (and equally another person, whose preference is the exact opposite) but as I said, that’s each one taking a call on how far they will follow utilitarianism’s conclusions.
Independently, there are several reasons why shifting the focus strongly to invertebrate welfare may not be the best approach but those are not necessarily incompatible with utilitarianism.
It is possible I am quoting out of context here but there was this sentence in your piece:
At least on the face of it, it seems like you are suggesting recourse to practical wisdom to solve some of these problems. In your comment, however, you are indicating that alternative ethical theories are possible but on re-reading your post, I was unable to come across an example of such a theory being applied to resolve one of these incommensurability dilemmas.
As you have noted yourself, with regard to the question of eating some meat in a scenario where doing so makes an individual a lot more productive (and given that there are no simple plant based substitutes that seem to do the trick so far) and donate more, I am in agreement here that it makes sense to do so.
But anyway I get the point here: there are surely other scenarios where I would be unwilling to accept the conclusions of raw utilitarian calculus. And I am perfectly fine with that but more importantly such exceptional situations would not be a reason for me to abandon utilitarianism completely.
I agree with your largely that we cannot take decisions based purely on a one-dimensional utility function. Often that utility function itself isn’t well-defined, doesn’t take into account second order effects, has only expected value and not the probability distribution of the outcomes, ignores deep uncertainty, etc. I also sure that we should apply common-sense considerations have a part but I wouldn’t rely too heavily on that either.