Epistemology

Absurdities of Immaterialism Or, A Reply to T. W. P. Taylder's Pamphlet, Entitled, “The Materialism of the Mormons or Latter-Day Saints, Examined and Exposed.”

Meditations on First Philosophy

Our Intellectual Strength and Weakness

The Pleasures of Ignorance

Thinking as a Science

The Philosophy of Evolution

Life and Matter: A Criticism of Professor Haeckel's “Riddle of the Universe”

Lectures on Popular and Scientific Subjects

Fichte's Science of Knowledge

Phaedo

The World Turned Upside Down

The Philosophy of the Conditioned

On the Nature of Thought

Aphorisms and Reflections from the works of T. H. Huxley

Rationalism

Luck, or Cunning, as the Main Means of Organic Modification

Knowledge for the Time

Modern Skepticism: A Journey Through the Land of Doubt and Back Again

How Do We Know

Theology's Epistemological Dilemma