I have a friend who is an avowed leftist, but his belief system is based solely upon vaguely understood soundbites. During a discussion, I asserted that many of FDR's policies were almost the literal equivalent of digging ditches and then refilling them, to which he replied, "Well, what's wrong with that?"
I honestly didn't know what to say. Somehow the answer of 'It's not the market-allocated use of resources and therefore is inefficient and artificial' didn't seem to fit. To someone who does not read economics and is still blinded by the linear thinking of statism, how do you argue against something simple like that?
1. Ask him if everything people need happens magically by itself, or do people actually have to work to get things done.
Does someone have to make the clothes he wears, or do they drop down from the sky?
2. OK, now if everyone got free money and did not have to work, what would happen to the stockpile of stuff we have? Would there be less t-shirts etc to go round, or more, or would it stay the same?
3. Is there a differennce between getting free money and getting money to do something nobody benefits from, like digging and undigging ditches?
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It's easy to refute an argument if you first misrepresent it. William Keizer
In your particular scenario I would ask the person a series of questions until they realize how absurd their belief is. Digging ditches and refilling them is absurd, so it shouldn't be too hard to think of questions which point out how it is absurd. It's a good thing really that his understanding is only minimal, if he were knowledgable then it would be much more difficult, in that the more rational the person the more they can justify their irrational beliefs.
If someone trully believed that the best society is one in which the most ditches were dug at all costs then yes, you would have no argument.
Instead, you should inquire what that person values and then explain why a libertarian society would provide it better than any other.
Send him a video of the Broken Window Fallacy with a nice animation.
Jack Roberts: Great video but showing it to someone isn't necessarily going to make them understand. Did you read some of the comments to that video? Some people simply don't get it, for whatever reason.