Since the early 1900s, it has been believed that in order to assign a particular label to an individual, that the accuser must too share those same traits. Such an idea has practically been as close to the bedrock of society as any other assumption for nearly a century.

But a university study spanning two decades has led scientists to conclude, quite resoundingly, that it does not, in fact, take one to know one.
“I know we’ve been taught this since we were small children and it does seems quite intuitive, but it’s simply not the case,” says California Institute of Technology professor Perry William Herman. “A young child can call Robin Williams “hairy”, while not being hairy himself. Kelly Ripa can call Governor Chris Christie a “large man” without actually being a large man herself. Though she’d never say anything like that because she’s such a sweetheart. Wait, am I now a sweetheart? See how that works? Some guy…any guy…on the Jacksonville Jaguars could say that Peyton Manning is a good quarterback. I think we’re on the right track with this now.”
The scientists believe that this glaring defect in the understanding of human interaction may have been holding back potentially huge societal gains for many decades.

You can’t argue with science, people.
So I suppose next you’re gonna tell me it doesn’t take two to tango.
Yes, but for those of us who are slow on the uptake, “It takes one to know one” is such a natural comeback when someone calls you a name. Are we now deprived of that?
I have long suspected this.