You...”doubt it”? I guess the issue is settled, then. I’ll take it that the underlying argument is “government bad, private good”. It doesn’t really contribute anything, but at least we can guess at the reasoning.
"Doubt it" is pretty much a clear invitation to present arguments.
Present an argue against what? “Is not!” doesn’t give a lot to work with. “Doubt it” does a fine job of presenting one’s biases, but it is most certainly not an invitation to stimulating discussion, quite the opposite.