Robert Hannas The Rational Human Condition is a five-volume book series, including: Volume 1. Preface and General Introduction, Supplementary Essays, and General Bibliography Volume 2. Deep Freedom and Real Persons: A Study in Metaphysics Volume 3. Kantian Ethics and Human Existence: A Study in Moral Philosophy Volume 4. Kant, Agnosticism, and Anarchism: A Theological-Political Treatise Volume 5. Cognition, Content, and the A Priori: A Study in the Philosophy of Mind and Knowledge The fifth volume in the series, Cognition, Content, and the A Priori, was published by Oxford University Press in 2015. So, with the present publication of the first four volumes in the series by Nova Science in 2019, all five volumes of The Rational Human Condition are now available in hard-copy and as e-books. All five books share a common aim, which is to work out a true general theory of human rationality in a thoroughly nonideal natural and social world. This philosophical enterprise is what Hanna calls rational anthropology. In the eleventh and most famous of his Theses on Feuerbach, Marx wrote that philosophers have only interpreted the world in different ways; the point is to change it. Hanna completely agrees with Marx that the ultimate aim of philosophy is to change the world, not merely interpret it. So, Marx and Hanna are both philosophical liberationists: that is, they both believe that philosophy should have radical political implications. But, beyond Marx, Hanna also thinks that the primary aim of philosophy (understood as rational anthropology) and its practices of synoptic reflection, writing, teaching, and public conversation is to change lives for the betterand ultimately, for the sake of the highest good. Then, and only then, can the human race act upon the world in the right way. The four volumes of The Rational Human Condition will therefore appeal not only to philosophers, but also to any other philosophically-minded person interested in the intellectual and practical adventure of synoptic, reflective thinking about the nature of our rational, but still ineluctably human, all-too-human lives.