If you've hung out around anarchist spaces, left or right, you've probably had a taste of the bitter dispute going on between lefty social anarchist types and so-called anarcho-"capitalists" (yes, I put the right word in scare quotes). On the right, the basic justification is this idea that capitalism, or at least anarchistic capitalism, is essentially good because it is voluntary. Basically, any social relationship is more or less justified as long as all of the participants can get out of dodge and associate with someone else if it doesn't go their way.
Thus, says the ancap, no one is really forcing you to participate in capitalism or wage labour. There are no police who will come and take you away if you don't take part. Whether or not viable alternatives to the capitalist mode of production exist is secondary -- not the boss' problem.
Now, naturally, anarcho-communists and the like take pretty big issue here. The communist sees the threat of starvation or whatever as essentially coercive even if the ancap doesn't intend to directly force anyone to do their bidding. That threat is enough to render the capitalist wage relation as involuntary and exploitative.
I can't help but find error in both sides. I'll agree with the capitalist that wage labour is essentially voluntary, but I don't exactly think this ought to be our only criteria for a "just" society (I can imagine of a lot of essentially voluntaristic arrangements that I'd like nothing to do with, and I can see ways that this line of thinking leads us back to social contract type justifications for the state).
I also think the communist critique is essentially insufficient for the market anarchist perspective, so I'd like to present an alternative.
So, lets assume, for a second, that the philosophical underpinnings of voluntaryist anarchism are all correct (as a thought experiment, since I don't endorse this line of thinking). No one is coercing anyone to take part in capitalistic wage labour, since there is no direct threat of violence. Despite this, there is no obligation on the part of the capitalist, in the form of taxes or charity, to support those who might fare badly as a result of refusing to take part. The obligation falls on those who wish not to participate. If you don't want a boss, it's your job to find a way not to have one.
As a mutualist, creating alternatives to capitalism is my main goal to begin with. If the obligation is on the people to create alternatives to wage labour, then let them create them. Surely, if a voluntary world is good, a voluntary world with more choice is better. Essentially, the capitalist argument here is one which, by its very nature, goads people into creating alternatives to capitalism.
The capitalist says "if you don't like it, make your own".
The mutualist says "we don't like it, so we're going to make our own".
Voluntaryism, as a result of its own rhetoric, tells us that we must create socialism ourselves. We wholeheartedly agree.