We've been thinking about the core concept behind «boundaries» extensively, and going forward we're going to stop using the term "boundaries" (alone) but use the term "«boundaries/membranes»" instead.

Summary: We've found that whenever try to use the word "boundaries" with others in lay speech, our explainees have had trouble. We think this is because the word "boundaries" in English is overloaded with different definitions, some of which directly conflict with our intended meaning. Critch suggested "membranes" as an alternative term in his first «boundaries» post, and we suggest using that instead.

Difficulties with using the word "boundaries"

The definition of "boundaries" used in common social situations (preferences) means something different than «boundaries/membranes»

We've found that the common use of the word "boundaries" is very confusingly related to the «boundaries/membranes» concept.

For example, if you hear someone say, "Hey, you yelled at me and that crosses my boundaries!", this is very not what «boundaries/membranes» is about.

Basically, everything in this post — which describes people setting social rules about how to interact with them according to their consent or preferences — is exactly what we don't mean by the technical term. Another example: this post is not about the "boundaries" that we mean: This post talks about "boundary" rules being variable, which we'd likely call "preferences"— meanwhile we think the concept at hand is is independent of any particular agent.

Basically: "crossing (boundaries : social requirements enforced by someone)" does not imply "crossing «membrane-boundaries»".

And that's annoying because every time we explain the concept to someone using the word "boundaries", we have to qualify, "it's called boundaries, but it's not about the normal kind of boundaries, but it's also not unrelated, but please just ignore that for now" lest they get understandably confused. Ugh.

(Also, this exact conflation delayed Chipmonk's understanding of «boundaries/membranes» for the entire month of December!)

Note: Critch and we seem to agree that the concept is distinct from preferences. He says so in his Part 3b:

That's because my goal is to treat boundaries as more fundamental than preferences, rather than as merely a feature of them.

The definition of "boundaries" used to mean inert separation means something different than «boundaries/membranes»

There's one definition of the word "boundary" that means "a line that marks the limits of an area". However, in practice we find it useful to break this into two cases:

when the boundary is maintained / defended / autopoietic (when the boundary is in the territory)
- eg the membrane around a bacterium
- eg the territory that a country's military defends/asserts around itself
when the boundary is inert / subjective (when the boundary is in the map)

These are different: In the former case, there is autopoietic pressure (because if you don't defend your membranes, you die), in the latter case a line has been drawn in the sand. These are different, and doing this conceptual disambiguation whenever we use the word "boundaries" is annoying. Ideally, we'd just use a different term without this baggage.

Why use "membranes" instead?

The term "membranes" was originally proposed by Critch in «Boundaries», Part 1: a key missing concept from utility theory (bolding ours):

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:
a cell membrane (separates the inside of a cell from the outside);
a person's skin (separates the inside of their body from the outside);
a fence around a family's yard (separates the family's place of living-together from neighbors and others);

(Wikipedia: Membrane: "a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles")

But Critch chose not to use "membranes" saying:

I want to focus on boundaries of things that might naturally be called "living systems" but that might not broadly be considered "agents", such as a human being that isn't behaving very agentically, or a country whose government is in a state of internal disagreement. (I thought of entitling this sequence "membranes" instead, but stuck with 'boundaries' because of the social norm connotation.)

But we disagree with Critch on these last points, and so this is probably why we're willing to choose the term "membranes" even though he isn't.^[1]

But we quite like the term. The word "membrane" is otherwise broadly used to refer to something that is independent of any particular agent (usually it points to something physical, eg a lipid bilayer). And we do think that concept at hand points at something that exists in more than just the mind of some set agents (e.g.: unlike human agreement or preferences).

And we don't think the word "membranes" comes with anywhere near the explanatory baggage that "boundaries" does. This isn't to say the word "membrane" is perfect, however— for example, it's not immediately obvious that the word "membrane" could refer to something nonphysical, eg an informational membrane/boundary.

Still, maybe there's an even better word (or frame) to use than "membranes" ("eg ownership"?, "sovereignty"?). Let us know.

^{^}
For instance, I (Chipmonk) think «membranes/boundaries» are inherently autopoietic. For this reason, I'm pretty confused about where the «boundaries/membranes» might be in some of the examples Critch gives in «Boundaries», Part 2. E.g.: Where are the membranes in "work/life balance"?