- Thomas Szasz
- Garret Keizer
- Ronald Dworkin
- David Rothenberg
- Helena Norberg-Hodge
- Joel Kovel
- Michael Taylor
- Nadine Strossen
- Charles Fried
- Lucy Kavaler
- Gary John Percesepe
- Michael Fogler
- William Voegeli
- Jonathon Porritt
- Michael Freeden
- John Herman Groesbeck Pierson
- Gay Hawkins
- Andrew Price
- Andrew Earles
- Jay Nash