Is this dichotomy warrented? A lot of people think so (e.g. every author of every biology text book I've read), but I would say no. Most people would point out that the difference between natural selection and sexual selection is that in sexual selection, the fittest don't necessarily have reproductive success. But how do you define fitness apart from reproductive success? You can't.
That is why I like to speak of natural selection without using references like good, better, best ( or fit, fitter, fittest). I prefer the definition of: differential reproductive success of organisms due to inheritable traits. If this definition is used, I see no difference between sexual and natural selection.
Where am I wrong?
ps. I'm writing this during an Ecology cram session so my mind might not be working right.