This is Part 1 of my «Boundaries» Sequence on LessWrong.
Summary: «Boundaries» are a missing concept from the axioms of game theory and bargaining theory, which might help pin-down certain features of multi-agent rationality (this post), and have broader implications for effective altruism discourse and x-risk (future posts).
Epistemic status: me describing what I mean.
With the exception of some relatively recent and isolated pockets of research on embedded agency (e.g., Orseau & Ring, 2012; Garrabrant & Demsky, 2018), most attempts at formal descriptions of living rational agents — especially utility-theoretic descriptions — are missing the idea that living systems require and maintain boundaries.
When I say boundary, I don't just mean an arbitrary constraint or social norm. I mean something that could also be called a membrane in a generalized sense, i.e., a layer of stuff-of-some-kind that physically or cognitively separates a living system from its environment, that 'carves reality at the joints' in a way that isn't an entirely subjective judgement of the living system itself. Here are some examples that I hope will convey my meaning: