Voluntaryism is based on the idea that you don't own other people, in whole or in part.

Rights are those things, which already exist and belong to each individual in equal measure. They are unalienable. That is, they cannot be transferred, taken, or given away. They can be violated; but they cannot be provided because they already exist. Further, if one assumes that rights may be given by the state (or granted by law), then that is also to assume that they may be taken away by the state. In which case, they were never rights at all but were at most, legal privileges. No state needs to exist to give me permission to live. I live already. My right to live was not granted to me by law, nor can the law justly deny me the right to live. - Samantha Lindsay, What is Just Law?

Axiomatically (see Rothbard, Rand, etc.) you own yourself. This implies several things:

These rights also imply the Non Aggression Principle.

Although voluntaryism is politically (meaning, answering the question of where force is justified) similar to anarcho-capitalism, the article How Voluntaryism Transcends Anarchism expounds on how it can influence beyond politics and economics into culture and education, moving from "What do I have the right to do?" to "How can voluntaryism be applied toward a harmonious and productive society?"

Also see:

Introduction to Voluntaryism: The Art of Not Being Governed by Peter Miller
Fundamentals of Voluntaryism
Wikipedia page