"Nobody in their right mind doubts that smoking causes lung cancer -- no causal link has ever been more conslusively established by more scientists doing more research."
Then simply provide the reason why some non smokers get lung cancer and not all smokers get lung cancer.
I don't know. How come some straight monogamous people get AIDS, while some gay men who have anonymous unprotected anal sex with hundreds or thousands of partners stay negative?
-1- Tobacco is by far the leading cause of lung cancer. But, as the asbestos industry knows, it isn't the only cause.
-2- Sometimes smokers -- like bathhouse goers -- just get lucky. The odds, however, are pretty slim.