Is Trump a Liar or a Fool

Trump is a businessman. He lives on telling people what he thinks they want to hear. To him, lying is a skill, not a flaw.

What he hates is being called ignorant. Not outing him as being wrong or mistaken gets under his skin. It is high risk, because you are telling his supporters that they may be ignorant. These people are not voting for Joe anyway, so it is literally a no risk strategy.

Let's give it a whirl. Should Biden say it - maybe in the second debate. Surrogates need to start saying it now. You cannot educate his voters on his stupidity until you call him stupid. 

The people around him are lying to cover up his lack of knowledge, even when they know better. Point that out too, as what they say enables stupidity on a large scale. The problem is not partisanship, it is people believing stupid things because other people won't say that what Trump is saying is stupid. Start saying it.