The slippery slope arguement is often used instead of logic to scare people into thinking a certain way. IF you can connect a to c through b, then it is a valid arguement. I don't see that very often though.
In the case of smoking, I'm all for public area bans. I am an ex-smoker and now cigerette smoke makes me physically ill. I shouldn't be subjected to it out in public. Like the old saying, "Your rights end and the tip of my nose (or lungs)" Even if second hand smoke was not bad for a person, a person shouldn't have to deal with it. Now in a person's private domocile, I don't care much what they do. It would only effect me if I went to thier place, and then I knowingly enter a smoker's home. An employer can decide whether smoking on premises is allowed or not.
Ah, but the argument seems to hold water. The ban I mentioned is not on workplaces or in public, but in the home.