Full Idea
Smoking disposes towards cancer, and has its way in many instances. The existence of some smokers without cancer, however, does nothing to falsify this dispositional claim.
Gist of Idea
Smoking disposes towards cancer; smokers without cancer do not falsify this claim
Source
S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 7.5)
Book Reference
Anjum,R.J./Mumford,S.: 'Getting Causes from Powers' [OUP 2011], p.165
A Reaction
Indeed, falsification by one instance will only work against absolute and universal claims, and nature contains hardly any of those.