As others have said, point out the morality and if he doesn't see force as immoral you'll have to prove to him it doesn't work well for both parties.
DaveDoggOwns:
1) The rich have more purchasing power than the poor and the middle class, so the DRO's will always tilt in their favor. Therefore, DRO's are prone to corruption regardless of free competition.
This is an effect of the state. In a market the middle class will probably eventually obtain the most purchasing power.
DaveDoggOwns:
2) When people want to help the poor, they do not want to tax themselves they want to tax the rich. Just becuase people are willing to vote for the welfare state doesn't mean they intend to provide private charity in the absence of a state. So you can't use that fact that most people want to help the poor in the statist society as evidence that people will want to help the poor in a free society.
It doesn't matter what they want. The middle class is being taxed the most regardless of whether they'd rather have the rich taxed or not. And ask him/her this question. We'll assume their income is taxed at 40%. "If your paycheck increased by 40%, would you be more willing to spare money to the poor?" If they don't obviously they don't want to help the poor so....... If they would be willing to, then the government is unnecessary to help the poor. And that example isn't even taking into account how much your purchasing power would rise without taxes......
DaveDoggOwns:
3) You are not supporting poor people's freedom if you do not help them. (ie me the socialist am more libertarian than you)
Well you are not supporting everyone else's freedom if you want them to be forced to indirectly support poor people.
DaveDoggOwns:
4) You do not believe in equality of authority if you do not believe in equality of socioeconomic conditions. (ie everyone has the same rights, but not everyone recieves the same benefits from those rights)
It's completely idealistic to suggest we could ever redistribute resources evenly between people. It's impossible from the standpoint that it takes a government that thorough (and one willing to eventually step down from power), and it's impossible because new children being born would constantly change the amount of resources any one person would be entitled to. The government creates more inequality of socioeconomic conditions.
DaveDoggOwns:
5) The free market is not a money democracy. Some people have more purchasing power than others.
He really doesn't understand the free market if he's saying it's not a money democracy. Say a store is on a budget of 5000$ for all new shipments. Say they normally buy $500 worth of carrots per shipment. If carrots start to sell more frequently than usual, maybe out of that $5000 they'll use $1000 of it for carrots the next time. Not to mention, that original $5000 might go up from increased profits on a given shipment or overall business expansion.