In presidential politics, ideas that are simple and straightforward seem to be winning voters. When it comes to fossil fuels, politicians have long kept things simple: Republicans tend to be for them, Democrats against them.
But by lumping all fossil fuels together in this way, we resist an important truth: that a nationwide ban on fracking would almost certainly be bad for health and the environment.
The reason is not complicated. It is based on two unassailable propositions.
First, in the United States, we rely on the market to supply our energy needs. We use the least expensive fuels to make electricity, within the limits of the law, environmental regulations and requirements of the electric grid. When natural gas is inexpensive relative to coal, we burn more natural gas. When coal is the less expensive fuel, we burn more coal.
In many parts of the country, coal and natural gas compete directly with each other. In fact, during the past 10 years or so, as the widespread use of fracking made natural gas less expensive than coal, natural gas gained electricity market share at the expense of coal.
The second proposition is that burning coal is much worse for public health and the environment than burning natural gas.
Putting aside climate impacts for the moment, the other emissions from coal-fired power are orders of magnitude more deadly than those emitted by other sources. That is why when the Environmental Protection Agency estimates the benefits associated with reducing fossil fuel combustion, harm from non-greenhouse gas emissions dominate their estimates.
No one in the anti-fracking community really disputes this enormous harm disparity between coal combustion and natural gas combustion, nor do they dispute that the former emits twice as much carbon dioxide as the latter. However, they do claim that natural gas is nevertheless worse for the climate if we consider leakage of methane (itself a potent greenhouse gas) from natural gas production and delivery.
But this claim is disputed in the scientific community, and the EPA's current best estimates contradict it.
In truth, we don't know how serious a problem methane releases from natural gas production is. The science is not yet in. To help answer this question, the Environmental Defense Fund is organizing a massive multi-study effort to identify and quantify methane releases. But it has not endorsed the anti-fracking activists' cherry-picking of the science or their hasty judgment that gas is worse for the climate than coal.
Whatever the eventual findings, they are unlikely to undermine the conclusion that burning natural gas is less harmful to health and the environment than burning coal. That doesn't mean we ought to burn natural gas; what if we could run the grid entirely on renewables, for example? We can't - at least not yet.
But even if we could switch to 100 percent renewable sources right now, we won't.
Why? Because politicians seem disinclined to force rapid, deep de-carbonization on the American electric system. Until and unless that happens, we're stuck with the reality that fossil fuels, nuclear power and renewables compete on price in electricity markets.
There are certainly other reasons why you might rationally oppose fracking in your neighborhood: It brings temporary but sizeable disruptions such as truck traffic, noise and odors. But local effects ought to be for locals to balance.
Nationally, fracking has made natural gas cheap, and so we are burning less coal (and killing fewer people) -- for now. But make no mistake: Coal is not dead, despite what you might have heard.
For now, coal still clings to its position as the predominant fuel in our electric generation mix. It is still competing for market share and for the right to continue to produce the dirtiest and deadliest electricity of all.
And railing against "fossil fuel" on the campaign trail won't change that. Phasing out nuclear power, another part of the Sanders platform, would remove the other major generation technology with which coal competes.
It is true that recent EPA rules aim to make coal-fired power more expensive. But the two rules that would impact coal-fired power most significantly remain in legal and political jeopardy and may never take effect.
In view of all that, do we really want to force our presidential candidates into ill-advised policy commitments that work to the benefit of coal in electricity markets? I don't think so.
David Spence is a professor of business, government and society in the McCombs School of Business and professor of energy law in the School of Law at The University of Texas at Austin.