> My original statement was to say that smoking nicotine is the leading cause of preventable death. See, you've assumed that A implies B means B implies A agai

> My original statement was to say that smoking nicotine is the leading cause of preventable death. See, you've assumed that A implies B means B implies A again. Smoking tobacco is the leading cause of preventable death. Nicotine is in tobacco, but that doesn't mean you can replace "Smoking nicotine" anywhere you see "Smoking tobacco." Hope that clears it up.