Do stereotypes have any truth to them?

[Sheldon]

Well I don't want to leap to ad hominem, but yes the reasoning on display is poor, filled with unevidenced rhetoric and hyperbole, but maybe the poster is young. I know that I would not have recognised common logical fallacies, or understood their implication until I was in my 30's. Though of course I was horrified to realise how poor my reasoning was as a result, and have tried not to make such errors since, and more importantly to honestly admit to errors and correct them...

Which by the way @Jamiesmithie is precisely the point I believe Silver was making, that one should have the integrity to accept when one is wrong, and to admit it.

Implying that Jamie may not be the sharpest knife in the drawer isn’t necessarily an ad hominem. That would only apply if we said his positions were wrong because he’s desperately, dangerously stupid.

The opposite is the case here - Jamie’s positions were wrong before he ever met them. The fact that those positions themselves are desperately, dangerously stupid has nothing to do with Jamie - his is an independent stupidity.

Boru

For clarity I wasn't suggesting it was ad hominem, I worded it poorly perhaps, I was just wary of heading in that direction by focusing on him rather his "arguments" such as they are. 

I'd also say that offering demonstrably stupid claims, does not in and of itself make one stupid, and of course being poorly educated doesn't necessarily mean one is stupid either. 

I agree about his claims though, woeful stuff. The real irony is it takes just a few minutes of cursory research to disprove them as well, so he could have easily investigated this himself. The claim he is happy to revel in poor reasoning might simply be an attempt at face saving of course, no one enjoys appearing foolish.