An editorial in Politico by William Bennett and Christopher Beach highlights the irony of the policy positions held by many people on the progressive left (something I also point out in the Food Police).
The very same year, for example, that Colorado legalized marijuana, the Colorado Senate passed (without a single Republican vote) a ban on trans fats in schools. Are we to believe eating a glazed donut is more harmful than smoking a joint? California has already banned trans fats in restaurants statewide, but now is on the brink of legalizing marijuana statewide come November. Former New York City Mayor Michael Bloomberg supported New York Gov. Andrew Cuomo’s effort to decriminalize marijuana in New York State, while at the same time supporting a ban on extra-large sodas. A 32-ounce Mountain Dew is bad for you, but pot isn’t?
The logic is dumbfounding. For many years, health-conscious liberals have waged a deafening, public war against cigarettes. Smoking bans in public places like restaurants and bars have been enacted in states all over the country. Recently, New York City, New Jersey and several other cities and states have extended those bans to include the newest tobacco fad—e-cigarettes. Yet, when it comes to smoking marijuana? Crickets.
What explains this obvious paradox?
They don't actually answer their own question - later saying simply that "The answer is not clear, and there may not be a good answer at all." I think there is an answer.
One way to think about these sorts of issues is to turn to ideology scales. A common view is that people's ideologies can be explained by where they fall on two dimensions related to views about economic freedom and personal freedom and willingness to use government force in these two areas. In this framework, a "liberal" wants personal freedom (abortion, gay rights, etc.) but wants to restrict economic freedom (by, e.g., setting minimum wages). Conversely, a "conservative" wants to restrict personal freedom (outlaw abortion and prohibit gay rights) but wants economic freedom (e.g., no minimum wage). I think one has to augment this model to provide an account of what's going on in this case.
Here we have two health-related issues: smoking marijuana and eating transfats. What would possibly rationalize supporting the legalization of one and the prohibition of the other? I think it has to with people's heuristic thinking about whether companies are good or bad and whether government is good or bad - or stated differently whether businesses or government is more likely to be corrupt. I think many on the left see transfats as bad because they're sold by big-bad food companies who will kill us just to make a buck, whereas marijuana (at least at present) doesn't have ties to big business. Thus, it is interpreted as a personal freedom issue by many on the left. Conservatives, by contrast, are probably less likely to want to ban transfats because it is seen as an intrusion of "bad" government into the economics sphere. Conservative's support for marijuana prohibition likely comes about from their willingness to use government force to regulate personal/social issues.
Interestingly, Bennett and Beach attempt to resolve their paradox in the Politico piece by seemingly arguing both transfats and marijuana should be banned. The other seemingly logically consistent stance is to suggest both should be legal, which is the position of many libertarians.
I suppose the economist could logically support one and oppose the other based on the results of a cost-benefit analysis or considerations of the extent of externalities, etc. Stated differently, a consistent utilitarian (or the economist who will use cost-benefit analysis as the final word on whether a policy is "good") could very well end up supporting one of these issues and opposing another.
The challenge, from the economic standpoint, is that many of these policies are advocated on paternalistic grounds - arguing that somehow people don't know what is in their own self interest, which seems to degrade the ability to know what is "best" from the consumers perspective, and thus the ability to even do a legitimate cost-benefit analysis.
My own view is that there is a legitimate role for government to play in researching and informing the public of the risks of smoking marijuana, eating transfats, etc. But, to step in and decide which choice should be made goes too far. It supplants the judgement of "experts" and politicians for the judgement of each person. If we are willing to dismiss people's ability to decide whether to smoke dope or eat transfats, it seems a short step to say that they also can't be trusted to make their own health care choices, or decide where they should live or what job they should take. Heck, why even allow these people to vote? That might seem a bit extreme, but I'm simply following the chain of paternalistic thinking to its logical conclusion.