  Wright accepted Hume's rejection of rational a priori knowledge and, following the positivist Auguste Comte (1789–1857), he applied Hume's lesson to theory in science. Wright regarded theory as a grammar or logical template for organizing sense experience, which was the only true origin of knowledge. As such, theory was a labor-saving device and usually mathematical in character. Some theoretical entities were real, but it is extremely difficult to settle upon any as surely real, given the method of science. That method is verification. Wright used the term verification to mean the testing of theories by deducing from them consequences that can be confirmed by direct perception, the “undoubted testimony of the senses” (PD 47). What are verified are predicted consequences of theory. This commitment to the sensory base of ideas both at the beginning and end of scientific investigation reinforced Wright's belief that utility is what makes both nature and human affairs intelligible. The principle of utility informed his understanding of Darwin's Origin of Species as offering not axioms for deduction but descriptive principles, in particular natural selection, that encompassed a wide range of disparate causes of change in organisms. From this vantage point on science, Wright became a penetrating interpreter and a brilliant defender of Darwinism in its introduction into the United States. In what follows, Wright's philosophy of science will be presented, highlighting the character of his empiricism as it is revealed through his understanding of induction. The influence of Mill's utilitarianism will be evident in his interpretation of Darwin, which is presented next. The nature of his positivism and his views on cosmology and natural theology are followed by a general characterization of his scientific philosophy.