Using the term as it is currently defined, not all markets need to be voluntary [1][2]

I’m talking about A being a subset of B, you are talking about B being a subset of A.

Ah, that’s my mistake, then. I didn’t initially read your comment as it stating that all voluntary interactions between people are themselves a market. I agree with that. However, I would still personally be more general in that all interactions between people form markets — they need not be voluntary. At the very least, I am not currently aware of an interaction that could not be thought of as a market.

Capitalism is defined to require that the markets be competitive [1], yes.

Same mistake.

Sure, but you’re still misquoting me. What I originally said was:

For a market to be capitalist it must be competitive

From this statement, I am stating that A implies B. You responded with:

you said only competitive markets form capitalism

Which is stating that B implies A. A competitive market need not be capitalist.

Voluntary exchange is a central characteristic of capitalism [1].

Looked to your reference and - same mistake.

This is part of the following quote which I read as being one thing:

you said only competitive markets form capitalism, thus voluntarism doesn’t necessarily mean capitalism.

I don’t really see how the latter half draws from the former half. Yes, capitalism is only formed by competitive markets, and yes voluntary interactions doesn’t necessitate capitalism, but I don’t see how the latter can be drawn from the former.

The way you are wording your replies is somewhat hard for me to follow, so, for me, they are likely susceptible to misinterpretation. I feel that I have to reply to them in fragments.

Not necessarily. For example, if the market were consumed by anti-competitive entities it is no longer competitive. An example of an anti-competitive entity could be a monopoly. Collusion is another example of a behavior which is not competitive.

It’s also no longer formed by voluntary interactions.

I disagree. You can choose to not do business with a monopoly. You can choose to not do business with entities that are colluding. Having choice implies voluntarism.

I would agree that basic principles of ancap do not mean capitalism as leftists describe it.

How are you defining “leftist” in this context?

One can say - people refusing to discuss the possibility of markets not intentionally rigged by some non-market force.

An interesting definition. At any rate, the original point is just a matter of the definition used for a word — “capitalism”. If they understand it as something different, then that is more an issue of poor communication.

Voluntarism and self-ownership.

I don’t understand why you are all of a sudden bringing up “self-ownership”, but yes if one fundamentally has self-ownership, then that implies that they can voluntarily take part in things. Do note that voluntarism isn’t all or none; you can have certain things that aren’t voluntary, eg taxes, and other things that are, purchasing goods and services. One could argue the degree to which one has self-ownership by how many non-voluntary things are required of them. Philosophically, one could perhaps always fundamentally have self-ownership — there may be social repercussions for an action, but there is no universal law preventing one from doing, or forcing one to do anything. It sort of depends on one’s frame of reference.