"But the debate is settled. Climate change is a fact[.]" That's President Obama, in his most recent State of the Union address.

This is an accurate statement of the climate change position. It is the sentiment behind the condescension leftists think they are entitled to show toward skeptics, abusively labeled "deniers." It was the attitude that "science guy" (meaning science entertainer) Bill Nye took toward Rep. Marsha Blackburn last Sunday.

But like many leftist arguments, "climate change" is undefined. It hovers in some kind of hyperspace above quotidian reality. It never leaves a footprint that can be measured. It isn't really an argument at all. It is an attitude.

But conservatives have to close with and defeat sentiments like this, because such statements can decide the fate of nations. That is the role of polemics.

Let's examine "climate change," the science of which is "settled." We don't have to go into Nobel territory. Let's go back to high school and use the tools we were given there. But with Thomas Sowell at our side.

We are experiencing climate change. As compared to what? If we are experiencing climate change, that has to be as opposed to climate stasis. So what is the definition of climate? What are its units?

If we are experiencing climate change, it has two parts: (1) climate change that is the norm and (2) climate change that is outside the norm. So the question of our experiencing climate change becomes, how much of the climate change we are experiencing is outside the norm of climate change? And, again, what units is that in?

We know that the climate of the Earth has changed over the last 15,000 years because it was that many years ago that the last ice age receded, allowing human civilization to be created. We know that within recorded history, Greenland has been both green and white. So how much climate change that we are experiencing today is that 15,000-year-vector, and how much is the vector generated by human activity?

Polemical summary: