system
Given the following post, respond as if you're commenting on Reddit:
human
Question on Marginal Utility Theory

Does the Marginal Utility Theory necessarily assumes that people are rational utility maximizers?
gpt
Marginal utility is like velocity: it's not so much a theory as a concept. It's the utility you get from a little bit more of something. Since marginal utility can be positive, zero or negative, it's not disprovable.