• A Short History of Freethought Ancient and Modern, Volume 1 of 2: Third edition, Revised and Expanded, in two volumes
• A Short History of Freethought Ancient and Modern, Volume 2 of 2: Third edition, Revised and Expanded, in two volumes
• Montaigne and Shakspere
• Rationalism
• The Evolution of States
• The Historical Jesus: A Survey of Positions