A hugely influential figure few people know nowadays, the American philosopher Hilary Putnam, died last week at the age of 89.
A mathematician by training with an expert knowledge of physics and computer science, he also wrote on ethics, logic, pragmatism, epistemology, aesthetics, religion, realism/reality and the mind-body conundrum. I recall that he learned ancient Greek in order to study Aristotle properly; no mean feat. The fact that he was a professor at MIT and then Harvard seems almost irrelevant.
I remember stimulating discussions of his “brain in a vat” thought experiment, and reading some of his dense papers on the philosophy of mind. They don't make them like that any more, and people with a fraction of his breadth of specialised knowledge and subject areas are described as polymaths.
Remarkably, as late as last year this old-world scholar was still giving lectures over Skype.