Epistemology

On the Significance of Science and Art

The Problems of Philosophy

Rationalism

Know the Truth: A Critique on the Hamiltonian Theory of Limitation

Ingersollia Gems of Thought from the Lectures, Speeches, and Conversations of Col. Robert G. Ingersoll, Representative of His Opinions and Beliefs

The Problem of Truth

On the Nature of Thought

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

Facts of Consciousness

The Ethics of Belief

Leibniz's New Essays Concerning the Human Understanding: A Critical Exposition

Organon – Posterior Analytics

Posterior Analytics

Of the Conduct of the Understanding

Outlines of Metaphysic

On Sense and the Sensible

Essays in Radical Empiricism

First Principles

Kant's Prolegomena to Any Future Metaphysics

Theophrastus and the Greek Physiological Psychology before Aristotle — On Sense Perception