Here. (HT Gene)
To put it bluntly, "screw Felix". I find it very odd that welfare even made it so big in economic science. Marginal subjective value informs personal decisions. That's the role it plays. Anything more than that is a little odd as a scientific matter.
Now as a practical matter we can probably say a little more, because it's a nice short cut to some conclusions. But there's no reason why we have to accept maximum total utility as the metric we're interested in. It's perfectly reasonable to say "let's just assume a more consistent utility function for everyone, (because screw Felix) and figure out what maximizes that". That's a defensible practical approach. And I suspect that's how welfare analysis sneaked its way into economic science. But it's highly dubious as a scientific matter.
Because as a scientific matter, there may be Felixes out there. But as a practical matter, we're well within our rights to not care, and most of us don't.
The universal explanation
3 hours ago