This strikes me as the most hilarious question, given that I’m a philosopher. Philosophy is all about respectful disagreement, and learning from disagreement. No decent philosopher simply parrots some other philosopher, so there must be disagreements somewhere in every case. I disagree less with J.S. Mill than with any other major philosopher, but I still disagree with Mill a good deal. Aristotle is insightful on some matters, not so insightful on others. As for Plato, Kant, Bentham, Sidgwick, and Rawls, my disagreements are larger, but still compatible with thinking that in some very major ways they were on the right track. I would not say that about Lord Devlin or James Fitzjames Stephen, but I still teach both, in order to learn from their arguments. If I didn’t disagree with a philosopher it would hardly be worth engaging with him or her, because there would be nothing to learn.