That is true only if you have debating skills on the level of Plato. There are many excellent demagogues who use sophistry to prove to you that 2+2=5. If you are not very good with logical fallacies you may fall prey to many of them.
Personally, I think Liberals believe there are far too many people like that in the world.
Consider: I grew up in Chicago. I've bought 2 cops, 1 alderman and a traffic court judge. Everyone in Cook County knows that the entire government structure is crooked. They assume everyone else in the country knows this. All the other democrats, nationwide, voted for a Chicago crook. So, what's the big deal? Democrats are either stupid or evil.
These are humanoids who believe in chem trails, black lung from trainloads of coal, global warming, fracking causes earthquakes and that Barak Obama is honest, although he will be the only one from Chicago in the last 150 years.
And yet, they believe in Eugenics, the most compelling justification ever stated for their own destruction.