He even argued that truths of Arithmetic were generalizations from experience. Ethics Mill was a utilitarian and basically a Benthamite. Utilitarianism was an attempt to resolve all ethical questions on empirical grounds. Moral duty could not, a la Kant, be derived from a priori reasoning. Ethical judgments have to be based on empirical generalizations about the usual consequences of particular kinds of actions.
Fishing is ok, because the angler's delight exceeds the fish's distress.
Mill never abandons the hedonic and individualistic bases of utilitarianism. Yet he advocates both in a wider, more flexible context. Second, he introduces a the consideration of the quality of pleasure in opposition to Bentam's quantitative notion. This introduces the idea of nobility of will and mind into the utilitarian calculus. Mill advocates the liberty of responsible action in view of a good involving many, but depending for its realization on the direct action and decision of the individual.