We should rename today's party of Trump as the 21st century Know Nothings.
The Republicans are really no longer Republicans - the have mutated into something far worse. They are now the party of Trump.
So, back in the 1850s, when the Whig party dissolved, they were replaced by the Know Nothing movement, which was was very much like today's Trumpians. It was anti-Catholic, xenophobic, and hostile to immigration, and started as a secret society. According to Wiki, adherents to the movement were to reply "I know nothing" when asked about its specifics by outsiders, which is how the group came to be called the Know Nothings.
Now, we have the party of Trump. When we think about what that party now stands for, and about the polarization in this nation, they are just like the Know Nothings were way back when.
And, when we think about the stupid things they say, their flawed reasoning, their cruel policies, it is clear how very, very ignorant most are.
Thus, they know nothing. The Know Nothings.