I don’t think you’ve just disagreed. When I say something has a marginal cost of $2.50, that doesn’t mean I’m considering the sadness inherent in having fewer shiny metal discs and green pieces of paper, it means there’s some opportunity cost which that money could have afforded which I would instead have to forgo.
I don’t think you’ve just disagreed. When I say something has a marginal cost of $2.50, that doesn’t mean I’m considering the sadness inherent in having fewer shiny metal discs and green pieces of paper, it means there’s some opportunity cost which that money could have afforded which I would instead have to forgo.