 His areas of concentration are Philosophy of Religion, Metaphysics, and Epistemology.His brother, Edward, is Professor of Philosophy at University of New Orleans.In his first book, "Hume, Holism, and Miracles", Johnson purports to have refuted David Hume's popular argument for the irrationality of belief in testimony of miracles (as can be found in his essay entitled "Of Miracles") as well as several reconstructions of Hume's argument (most notably that of Bayesian philosopher Jordan Howard Sobel).