Because Liberals always argue out of ignorance, it's simple to logically defeat them simply by having information. (Note: At that point they fall back on screaming, swearing and name-calling. Since they can't defend their positions with logic, they scream, swear, and name-call a lot.)
When it comes to taxation, Liberals/Democrats always want more, no matter how much we're already taxed. Because of the Laffer curve, their ideological aim is to punish rather than to actually increase revenue.
Here it is explained by an expert.