It was about 40 years ago that the first warnings about the danger of smoking were put on cigarette packs.

It was about 30 years ago that TV and radio advertising were banned for cigarettes.

In roughly the same timeframe, smokers were moved to the backs of planes.

In the following years, smoking was restricted further. First, it was in the workplace. Then smoking was banned on planes altogether. Later, it was most public places in a lot of cities such as parks and arenas. Now, it's getting banned in restaurants, bars, and other cases of private property.

This is an example of incrementalism, or of the slippery slope. No one would've predicted any of this 40 years ago but it happened (and as a non-smoker, I'm glad a lot of it did happen). Slippery slope are indeed real.