I definitely wasn’t making the argument that anyone was arguing for slavery, just that notional definitions of moral progress are much more complicated than simple economic metrics. There is so much more that goes into what is “right” and “wrong” than pure economic level, at a micro or macro level.

Now you might say I’m making a straw man of their argument, but then what are they even arguing then? I can’t figure it out. What does “advancement” mean? They alluded to social sciences having various measure of human happiness is and that a “Progress Studies” department could synthesize these metrics into... what exactly? Policy proposals? A religion? Metrics of human well being assume an underlying framework of morale agreement to begin with.

You simply cannot philosophically convert an objective metric into an “ought” without making a ton of morale assumptions. You cannot prove that your morality and values are better than anyone else’s because you will infinitely regress into definitions if what “good” means.