I’m reminded of the “lock box,” which was a largely unsuccessful political gambit promoted by Al Gore during his 2000 presidential run as a way to make Social Security tax increases more palatable. The idea was that we would ensure that taxes collected for this purpose would not be redirected, making it just one more tax increase.

My impetus has been the idea of so-called fax taxes, which would use taxation to make unhealthy foods more expensive relative to healthy foods. I haven’t been able to firmly endorse or reject the idea, which is another form of what has been known, for quite some time, as sin taxes.

I do think that raising prices on, say, sugary soda, will reduce their favor in the marketplace, and if ever a product deserved such treatment, it is the virtually benefitless sugary soda.

One of the counterarguments Big Food has used is that taxes of the magnitude that has been proposed would not work. Public-health advocates who propose such measures often don’t ask for what they they think is needed because their political calculations temper them. (A report just out from Oxford researchers says such taxes would need to exceed 20 percent to have an effect.)

Part of my hesitation over taxes on unhealthy food is that opponents can manipulate opponents of any tax to join them, even if they might agree that the globesity pandemic isn’t worthy of collective action of some sort.

Potentially, that strategy could be blunted by legally requiring that money to be used only for public health or some other unassailable cause, to be assessed by the Congressional Budget Office or some other credible, nonpartisan entity.

But that would only work if people trusted politicians not to subvert what they said in order to meet some new goal, and too many of us don’t trust politicians to do anything except serve themselves.