I think this oversimplifies and unreasonably quantizes what is a multidimensional spectrum of negotiation (aka micro-alignment transactions). All of these "types" of communication are valid, but only in specific contexts, both explicit and implicit.
Your example of a request/demand to take out the trash is a good one. There's a LOT to unpack there about the relationship, prior behaviors, and partially-agreed roles that you're each taking.
This is somewhat reflected in your closing,
Instead of following a rule of never using demands, I propose that the wise thing is to strive to use the ask that's best in a social context.
But without recognizing the underlying complexity, it's very hard to use this advice, as "best" is exactly as complicated as the rest of the concepts.
unreasonably quantizes
I'm not sure where that comes from. I don't apply quanities at all in the post.
There's a LOT to unpack there about the relationship, prior behaviors, and partially-agreed roles that you're each taking.
I do acknowledge that it requires a certain culture for a request to be take out the trash to be treated as one and not as a demand. You might very well live in a cultural enviroment where that's not possible.
This post is not about how to change culture but more about the options that exist.
Sorry to be unclear - I meant "quantize" not as just that it tries to make it a scalar quantity, but that it puts interactions into specific levels of force. But maybe I'm over-reacting a bit.
The request to take out the trash, in many contexts, is a mix of request, demand, and reminder. Any of "sorry, would you mind taking it out instead?", "yup, was just about to", "jeez! Okay, Mom!", "I think it's Joe's turn", or hundreds of other reactions can be appropriate. With very different levels AND TYPES of relationship changes as a result.
My main point is that there is value in being able to distinguish the different modes. The fact that there are examples where the modes are mixed up and there's no common knowledge between the participants of a discussion about what's meant doesn't refute the thesis.
we can also add a 5th distinction, Instruction - in a situation where it's expected that one person will tell the other what to do and the other will follow, but without negative consequences if they don't (as with commands). common in teaching and training situations.
Instructions aren't always appropriate. for example, if I'm cooking in a way i like and someone gives me unsolicited instructions i would be annoyed.
Also i would sharpen the definition of 'command'. many times when people demand something their response if you don't fulfill the demand is akin to punishment. but i still wouldn't call it a command. i think a command makes sense only from an authority figure in a situation where it's agreed they have authority over you (it can be that you personally don't agree but society decided they do).
I guess it's also possible for someone to give a command where they don't have the authority to, and that probably wouldn't be taken well.
I think instructions can be either invitations, requests or demands. In the case of cooking instructions, in many cases the annoyence will be driven by it being unclear whether or not the instruction was an invitation, request or demand.
When holding a rationality meetup and having a pair exercise, giving the instructions as an invitation can be helpful. It gives the pair the freedom to take another approach then the one I proposed to solve a problem when another approach seems to be better for the problem.
If my goal is to actually teach a specific mechanism I might request that the mechanism is used.
If a person constantly interupts me during my explanation of an exercise I might demand that they are silent.
There are multiple ways of asking another person to engage in an action. Many people don't reflect about the different kinds of asks, use the asks that their cultural conditioning dictates and don't get what they want. They might stay silent because they don't want to inconvenience the other person with a strong ask. Other times they express a strong ask and inconvenience the other person more than they desire.
Invitations, requests, demands and commands
This post explores the differences between invitations, requests, demands and commands. While sometimes people say "I request you to take out the trash" when they mean "I demand that you take out the trash" it's still useful to mentally distinguish the different kinds of asks.
An invitation is about giving another person an option to do something. If I'm holding a party and have a guest list, an invitation is a requirement to attend the party but I'm completely okay with people who would be welcome at the party not arriving. If the other person thinks they have a better option then the option that my invitation gives them, I'm not expecting them to follow my invitation.
A step above an invitation is a request. When I'm sitting in a room with high CO2 I might request that another person opens the window. If the person follows my request they are doing me a favor that I appreciate. If they however don't open the window that's also fine with me.
A step above a request is a demand. If I want to read a book that I lend a friend again, I might demand that my friend give me back the book the next time we meet. If the other person doesn't bring the book the next time we meet and doesn't have a good reason, I'm going to be a bit angry at them not fulfilling my demand.
A step above a demand is a command. If I'm in court the judge gives me a command to tell the truth. The command implies that there's a punishment when I violate it, even if I can present a reason for why I don't think it was a good idea to tell the truth.
Cultures
In the Ask and Guess culture distinction there's the idea that a culture either does their asks with invitations and requests or does the asks with demands and commands. In practice, people who are in a guess culture environment will often interpret the invitations and requests as demands. It requires cultural norms that allow invitation and requests to be made without being interpreted as demands.
On the other hand, it's a failure condition in cultures that focus on making asks via invitations and requests that people who make demands do it in the language of requests and get angry when their requests aren't fulfilled.
In English the word should is linked towards demands while must is linked to commands. Nonviolent-Communication labels demands as violent and proposes to get rid of demands in social interactions. While I do consider it generally valuable to use invitations and requests for interpersonal interactions there are cases where demands are appropriate.
In our Western world commands have little place in interpersonal interactions outside of organizations like the military that need to be able to get soldiers to follow commands reliably.
Instead of following a rule of never using demands, I propose that the wise thing is to strive to use the ask that's best in a social context.