I have had some success with the following technique in avoiding arguments, handing assertions, and focusing on education. Frequently when discussing voluntarism, you will be bombarded with uninformed assertions, most frequently centered around miss-education they received in public schools.

• "Roads can never be built in a free society"
• "There is no security or law without government"
• "Anarchists are naive and it will never work"

There are a variety of means of handing this monster, but recently I have had success with the following:

• "In order to avoid significant missteps, please ask questions before making assertions about a concept you are unfamiliar with."

The above delivery is slightly condescending, so feel free to modify it in the context of your discussion. Typically the way this works is:

• Me: "Describe voluntarism..."
• Statist: "Peasants!!!! Fear my uninformed assertion monster!!!"
• Me: "Call out assertion & then educate"

With the above model, I typically do not argue directly against their assertions, but rather focus on approaching matters from an educational perspective. This is valuable in avoiding traps that distract from core principles, ethics, and economics. If they step out of line, i may treat them as an unruly and ignorant pupil, for example....

• Statist: "But no one would ever fund roads because of market failure, bla, bla"*
• Me: "Your inability to imagine alternatives and innovate solutions in no way implies that innovative solutions do not exist. Again, please ask questions before making assertions."

P.S. The above method is typically used in a context where I wish to educate. In debates (which I typically avoid), I typically focus on the assertion, burden of proof, and asking questions instead.