The American philosopher John Dewey bared many of his seminal ideas in Human Nature and Conduct. Drawing on themes found in Charles Darwin’s On the Origin of Species (1859), one of the modern world’s most influential studies, Dewey defined human beings as creatures within the natural order who, like members of other species, were obliged to adapt continually to one another and to their environments in order to survive. In this context, Dewey argued that past philosophies had been too abstract and too concerned with constructing intellectual systems to serve humanity’s practical needs. Much like his fellow American philosopher William James, Dewey also believed that truth was what happened to an idea and therefore, that truth changed over a period of time. For Dewey, life began and ended in human experience; in other words, humans who used appropriate methods could successfully negotiate life’s confusing, obscure, and indeterminate situations. The key to coping with such problems, Dewey insisted, was using insight to define problems, establishing a set of possible solutions, determining the likely consequences of each possibility, and then evaluating the best possibility through observation and experiment. These flexible steps, which produced what Dewey called “warranted assertibilities,” were, he believed, as relevant to social reform as they were to laboratory science. The purpose of warranted assertibilities and the inquiries of which they were a part was changing specific situations. Ideas, in short, were instruments. Humankind, like other species, had no fixed natural end; therefore, events could be shaped by open-ended, democratized inquiry and the freeing of human intelligence. The greater the number of human alternatives, the freer humans could become. In Human Nature and Conduct, Dewey championed both naturalism and instrumentalism, upon which he elaborated later in his many writings. As a reformer, he earned international esteem for the fresh directions that he advocated in education and in the democratization of social and political institutions—a democratization that he regarded as essential to human adaptability and the problem-solving play of the human intellect.