Smoking is bad for you. Sugar-sweetened sodas are probably bad for you too. But taxes on cigarettes and sugary drinks are dumb and mean-spirited, and liberals should oppose them.

Smoking causes cancer, heart disease and emphysema. Despite this knowledge, some adults still want to smoke – and their decision should be respected, even if most other adults dont understand it. Levying punitive taxes on tobacco – as high as 400% on a pack of cigarettes – as if to help others make the “right” decision, is paternalistic and obnoxious. It’s well known that smoking causes disease – helping it cause poverty too is gratuitous.

Many are familiar with the argument: since society ultimately picks up the tab for the health consequences of smoking, society can rightfully tax it to reduce smoking rates. Milton Friedman rightly critiqued this as a slippery-slope to tyranny – that the sum of such policies will greatly erode liberty. But few realize that the math doesnt work either: smoking probably reduces government spending because smokers live shorter lives, and so collect less social security than they would otherwise. We should be glad to pay a premium for liberty – but it’s nice to know that we can let smokers smoke in peace without fretting over the bill.

Conservatives look stupid when rejecting gay love or marriage – seemingly unable to make the rather simple inference that gays can naturally and normally have romantic feelings for members of the same sex, even though such feelings can seem strange or repugnant to some heterosexuals. The inability to tolerate – much less acknowledge the validity of – preferences different from their own, reveals a fundamental lack of insight and imagination.

But liberals look just as stupid when they beat up on the working-class over their Marlboros and Coke Classic. Driving without a seatbelt is idiotic – but if informed adults want to go that way, they should have at it, free of state intrusion. It is in fact NOT at all obvious how one goes about weighing the trade-offs between unhealthy behaviors and shortened lives. You dont have to understand why someone else is willing to give up 10 or 20 years to smoke, eat badly, ride a motorcycle or skydive – but as a liberal, you must accept their informed decision, else you fall into the same species of error that conservatives make on gay rights.

There’s also a more modern, fancier slippery slope: that since smoking is addictive, we can dismiss the choice of adults to smoke because their decision is not consensual. We might treat smokers as people who have been duped into an addiction, and so disregard their apparent preference, and look for ways to help set them straight. Despite the efficacy of medical models for the treatment of drug abuse and addiction, invalidating the considered, informed decisions of adults is dangerous business. A liberal society demands that adults be given the benefit of the doubt.

Liberals are sometimes rightly critiqued as elites who are so sure they know better than other people, that they’re willing to substitute their judgement for those they deem to be in need of guidance. Smoking and obesity patterns follow class lines, with poor, uneducated working people far more likely to smoke and be overweight. Cigarette taxes thus seem as paternalistic as they are regressive, and feed the perception that liberals are out of touch with the working class.

Respecting other people means, above all, recognizing that their choices on activities that impact their own lives are valid per se. It is the government’s role to disseminate information so people can make the best possible decisions. But manipulating prices through tax policy to impact preferences is simply not a proper role for a liberal government. The decisions of informed adults should be respected, even if they are not understood.