I don't think people who smoke are any smarter than people who don't, or vice versa.

I think smoking can lead to deep thinking because it tends to make you more introspective, and it can give you a sense of wonder that makes you want to think about things. Sometimes it makes me feel very smart. But smoking can definitely impair your memory. I tend to want to think about things when I am high, and sometimes I can get some great ideas. But sometimes I can't even remember my great idea 30 seconds after I had it, so that is not really all that smart. Sometimes I can't read a book when high because I can't remember the begining of a paragraph by the time I get to the end, and that's not smart. Or I'll get so distracted my my own thoughts spinning out of control, that I can't follow the train of thought that someone else has written. And I have definitely done some stupid things when I was high that I would not have done when not high.

So it's hard to say what the effect really is. It makes you want to think and gives you new ideas, but memory and focus can be a problem.

One thing's for sure, some of the smartest people I have ever known smoke, and some of the dumbest as well.