Grace A. de Laguna was an American philosopher of exceptional originality. Many of the arguments and positions she developed during the early decades of the twentieth century later came to be central to analytic philosophy. These arguments and positions included, even before 1930, a critique of the analytic-synthetic distinction, a private language argument, a critique of type physicalism, a functionalist theory of mind, a critique of scientific reductionism, a methodology of research programs in science and more. Nevertheless, de Laguna identified herself as a defender of the speculative vision of philosophy, a vision which, in her words, “analytic philosophy condemns.” I outline her speculative vision of philosophy as well as what is, in effect, an argument she offers against analytic philosophy. This is an argument against the view that key parts of established opinion, e.g., our best theoretical physics or most certain common sense, should be assumed to be true in order to answer philosophical questions. I go on to bring out the implications of her argument for the approaches to philosophy of Bertrand Russell, Willard V. Quine and David Lewis, and I also compare the argument to recent, related arguments against analytic philosophy. I will suggest that de Laguna offers a viable critique of analytic philosophy and an alternative approach to philosophy that meets this critique.