I admitted myself that I was unsure of premiss 3 especially (and so, of the others also, but less)...
Now, when I say "one must" or "one ought to", I could've had formulated it in the form of a hypothetical imperative: one must follow...in order to be happy.
What I find interesting is that the premisses be critisized. IMO, premiss 3 is not very strong.
Maybe there are stronger reasons for practising buddhism. I'd be glad that somebody formulate them in a form of syllogism.
I can be more detailed in the premises
1°) Buddhism is the teaching of the Buddha
2°) The Buddha is the wisest person one knows of3°) The best teaching on how to be happy comes from the wisest person
4°) One must follow the better teaching to happiness
So one must follow buddhism.