If that's ad hominem I'm 100% ok with that.
One-line arguments about ad hominem, bandwagon, or appeal to authority, are all lazy arguments.
edit: In fact this exact conversation is an interesting example. John Lott is a highly decorated academic and has received praise from notable academics. In this case I used google to discover his history of deception. So in a way I'm using "yahoo answers" to argue against the phd. With John Lott the criticism is coming from enough sources I feel confident trusting they're true.
His research was one of the reasons I moved my family to the suburbs where violent crimes are excessively rare and committed predominantly by visitors from the urban centers.
If you read his entire wiki there are just a stunning number of red flags (the whole thing even, not just the controversies section). In this HN thread alone people have casually pointed out some obvious flaws. At the very least he's putting a lot of effort into spreading FUD about violent crime.
I really don't see how you can take him as a useful and objective source on these issues unless you're already coming to the conversation with some kind of anti-urban prejudice.
In some ways it reminds me of the conversation about child rapists and pedophiles. People lose their mind over the safety of their children when exposed to the community while ignoring that most of these crimes happen within their own families. It all just smells of a general fear of the vague and dangerous "other."
Hacker news will have to suffer for it.
https://en.wikipedia.org/wiki/John_Lott
Feel free to skip to the hefty controversy section.