J. R. Lucas

Philosophy is all interconnected. This allows someone who is an expert in political philosophy to comment on, say, epistemology or logic without committing the fallacy of irrelevant authority. This doesn't mean, though, that just because someone is an expert in one philosophical field, their opinion in other philosophical fields is just as valuable. Give philosophy's nature I think it's justified to give a philosopher the benefit of doubt when he comments on a philosophical topic outside of his usual focus, but ultimately you have to take it on a case-by-case basis. Bertrand Russell, for example, was an expert in the philosophy of mathematics, and used his credibility there to write books on other subjects such as the philosophy of religion and political philosophy. Unfortunately, it's obvious that he didn't know the first thing about the latter subjects. Anyone who has taken a Bachelor's level course in the philosophy of religion should be able to refute him.

J. R. Lucas on the other hand is one of those philosophers who brings expertise to every subject he approaches. This is partially because he takes philosophy to be a way of life rather than a method to win arguments. So he has written on logic, the philosophy of mathematics, the philosophy of science, the philosophy of mind, the philosophy of religion, political philosophy, the history of philosophy, ethics, metaphysics, etc. You can see a bibliography of his publications here. A list of his books shows his diversity:

The Principles of Politics
The Concept of Probability
The Freedom of the Will
A Treatise on Time and Space
Democracy and Participation
Freedom and Grace
On Justice
Space, Time and Causality
The Future
Responsibility
The Conceptual Roots of Mathematics
Economics as a Moral Science
Reason and Reality

Those are the books he's written by himself. He has also written books with other authors:

The Nature of Mind
The Development of Mind
Spacetime and Electromagnetism
Ethical Economics
An Engagement with Plato's Republic

As far as I'm concerned, Lucas is one of the most important and under-appreciated philosophers of our day. He has written on philosophical subjects so diverse, and yet with a mastery that I could never achieve if I focused my life on just one of them. For one thing, the man thoroughly understands Gödel's Incompleteness Theorems. These theorems are so notoriously complex that I suspect there's only a few hundred people alive who understand them. Yet not only does Lucas understand them, he is able to show that they render strong artificial intelligence and all forms of physical determinism impossible. If I spent my entire life on Gödel's theorems I still wouldn't be able to interact with them as thoroughly as Lucas.

Fortunately Lucas has posted excerpts from several of his books online, as well as most of his published articles. You can read his Reason and Reality in its entirety, as well as Ethical Economics. He is putting another book on the subject, Economics as a Moral Science, online as he writes it. so far he has chapters 1 ; 2 ; 3 ; 4 ; 5 ; 6 ; 7; conclusion ; and two appendices here and here. He has also posted several chapters from his The Conceptual Roots of Mathematics online: chapters 2 ; 4 ; 7 ; 8 ("The Implications of Gödel's Theorem") ; 9a (which replaces his previous chapter 13) ; 9b ; 10a ; and 14. An Engagement with Plato's Republic, co-written with the late great Basil Mitchell, has the introduction and chapters 1 ; 3 ; and 10 posted online.

I'm linking to all of these to invite you to join me in being a student of Lucas. Philosophy students are going to be writing dissertations on him 500 years from now.