"Dean talks about governments trying to alter behavior through incentives and disincentives. I agree. It's the behavior part we need to think a bit more about."
Well, the problem is that there are so many people who can't or won't take care of themselves and then you and I pay for it. Sorry- I'm opposed to that. I don't want to pay for the "disability" of some 5'8" 420-lb mollusc.
Especially the poor- hell, they're too busy surviving to even educate themselves well on political issues so that they can vote rationally, let alone learn about tobacco and high fructose corn syrup. That stuff is WAY down on their priorities list. (This is one good argument for a two-party system, that everyone would at least know basic principles of the parties and be able to vote their will. I don't buy many other arguments for two parties, though. Destroying the two-party system would resolve another 20% of what's wrong with the US...) We- well, me, at least- the wealthy, are much more informed on such issues and financially capable of caring for ourselves to a very high standard.
I'm rather annoyed when government fiat legislates on many issues, too. (I tend libertarian on social issues.) But I have no problem with simple incentives and disincentives. They're straightforward To implement, they work adequately, and they infringe on no-one's rights. Hell, as you all know I tend to the right on Second Amendment issues, and I'd have no problems with a tax on the firearms that particularly offend the hoplophobes- perhaps the same as is levied on fully-automatics weapons currently. (Believe me, there are LOTS of my fellow Second Amendment proponents whom I would prefer not to see armed with ARs...)
This all comes back to my "corporations are not people" argument. If we forbade corporations to purchase politicians I think that the sugar/corn/oil subsidies would go the way of the dodo, 40-oz fountain drinks would be banned, and sugar water would be taxed, all within the year. I think we'd all be better off, and that's really what it's about.
The "slippery slope" argument is not valid. It is an informal fallacy- a false argument, in logic terms. That applies to gun proponents just as much as to chocolate proponents. :) It is false because I said that we should tax sugar water, and doing so does not de facto lead to taxing chocolate. So, to answer your question- Yes, we can set a limit wherever we like- if that's sugar water but not chocolate, that can be done. It's not complex. Very few people chocoholic their way to obesity, anyway, so taxing it would be pretty pointless. Right now, sugar water and putting corn syrup in fecking EVERYTHING is the problem, so address it.