Admit it: Wearing that "Hope and Change" shirt back in the fall of 2007 made you feel pretty cool. Or maybe you feel the same way these days about your shiny Rand Paul Beats Headphone Skins.

"The brain processes cool in terms of its impact on our social identity," says Steven Quartz, co-author of Cool: How the Brain’s Hidden Quest for Cool Drives Our Economy and Shapes Our World. "[W]e buy products that reflect who we are and how we want others to think of us as well."

But it's not just the products we buy. The same often holds true of the candidates we buy into.

This wasn't always the case, of course. Just going back to the 1970s, Richard Nixon arguably wasn't cooler than George McGovern, and Gerald Ford definitely was not cooler than Ronald Reagan.

But lately, cool means victory. Our last three presidents were cooler than the six competitors they bested. Bill Clinton was cooler than George H.W. Bush and Bob Dole, George W. Bush was cooler than Al Gore and John Kerry, and Barack Obama was cooler than John McCain and Mitt Romney (and in the 2008 primary, Obama was cooler than Hillary Clinton, too).

Of course, cool can be in the eye of the beholder — but I'm sure that most liberals would concede that Bush was cooler than Gore, at least in the conventional sense, and that most conservatives know Obama is cooler than Romney.

And that's the thing about cool: You know it when you see it.

But what does cool really mean? According to researchers, there are essentially two types of coolness: The first involves "people who exude confidence and make everyone around them feel comfortable," while the second is a more rebellious form that manifests "a detached, effortless attitude defined in part by emotional control and a certain unflappable confidence."

Think of the 2000 presidential debate when Al Gore stood up and attempted to intimidate George W. Bush — an apparent effort to become the cool Alpha male in the race. Bush's dismissive nod demonstrated that "detached, effortless attitude." It became one of the election's most memorable moments. Bush seemed cool. Everyone — Democrats and Republicans alike — said they'd rather get a beer with Bush than Gore, to the point that it became a joke in The Onion.

And that brings me to the GOP's future. My last column questioned whether or not Republicans should nominate "an Obama of their own." Unspoken was how the concept of "cool" factors into all this. Like the products we purchase, the candidates we support say something about who we are (or, at least, who we want people to think we are). We might want to believe that our preference has to do with a candidate's policy positions, and in many cases it does. But it's also at least partly about cultural signaling. We all want to be seen affiliating with a cool brand, and we interpret what that cool brand is by means of our tribal identities.

In this sense, Republicans are faced with both a challenge and an opportunity. If a demographic shift has made it vital for Republicans to sell conservatism to more millennials and urban, cosmopolitan voters — and I believe it has — it makes sense to go for cool. Marco Rubio — who is young, handsome, and fluent in Spanish, sports, and pop culture — is cool. Especially compared to Hillary Clinton. Grandmothers (and grandfathers!) may be a lot of wonderful things, but "cool" isn't typically one of them, at least in the popular imagination.

And it's not just Rubio. Rand Paul is kind of cool, particularly among millennials who are socially liberal but wary of the intrusiveness of big government. Indeed, there might never be a better time for the GOP to steal the "cool" mojo from Democrats — who have tended to "own" the cool factor for the better part of the last 50 years.

If you put aside the historic nature of Hillary Clinton's candidacy — and that is a huge if — you are left with a candidate who has achieved extraordinary levels of professional success — and is undeniably uncool.

Now, here's the problem. Political campaigns try very hard to make candidates look cooler than they really are. Sometimes they succeed. Clinton could still win the cool race. Republicans should not assume they have this one locked up. The mainstream media is currently giving Clinton fits, but they will eventually attempt to come to her rescue, and undermine whomever her GOP opponent is.

Still, the fracturing of media, and the rise of alternative sources, has increased competition. No longer do a few mainstream media outlets have a monopoly on the news. That also means they no longer have a monopoly on defining what is cool. This, I suspect, means we will see through the spin and get a clear picture of who's really cool. And I'm pretty sure it won't be Hillary Clinton.