You can tell them that taxation isn't theft because taxation is legal and democratically decided, and theft is not legal. They will probably argue back, "in bo

You can tell them that taxation isn't theft because taxation is legal and democratically decided, and theft is not legal. They will probably argue back, "in both cases you're taking something by force," but there are lots of pairs of things that share some traits but not others. Sharing a trait does not make the two things the same thing (i.e. prison vs kidnapping, again, one is legal and one is not).