When Kant surveyed what the history of metaphysics had left behind, he saw a “stage of conflict” - a disconsolate landscape of edifices fallen into ruins (A 852-3/B 880-1). Most of the wreckage, when new, had been the proud work of the philosophers Kant called “dogmatists.” Kant never wavered in his admiration for their highest standards of construction: “the regular ascertainment of . . . principles, the clear determination of . . . concepts, the attempt at strictness in . . . proofs, and the prevention of audacious leaps in inference” (B xxxvi). The failure of the dogmatists lay not in their manner of building, he thought, but in their decision to begin construction on what turned out to be uncertain ground. They had neglected, he explained, to “prepare the field” (B xxxvi) - to conduct a “critique” or assessment of their own capacities. The failure of the dogmatists was, in Kant's view, a failure of self-examination. Socrates had long before insisted that the unexamined life is not worth living, but philosophical projects commencing with self-examination were especially characteristic of modernity. Descartes's Meditations is probably the best-known example.

In the final chapter of his Essay concerning Human Understanding, Locke divides all of human knowledge into three parts: the knowledge of things as they are; the skill of achieving what is good and useful; and the knowledge of signs. Locke calls the third part “logic,” “semiotics,” or “the doctrine of signs.” The present chapter is a survey and assessment of Berkeley's main contributions to this “great Province” (as Locke called it) of the early modern intellectual world. It was a province to which Berkeley attached particular importance and promise. In the seventh dialogue of Alciphron, his spokesperson Euphranor announces that he is “inclined to think the doctrine of signs a point of great importance and general extent, which, if duly considered, would cast no small light upon things, and afford a just and genuine solution of many difficulties” (ALC 7.13 [307]).

The most enduring comment ever made about George Berkeley was conveyed by Samuel Johnson to his friend James Boswell, who records it in the following story:

After we came out of the church, we stood talking for some time together of Bishop Berkeley's ingenious sophistry to prove the non-existence of matter, and that everything in the universe is merely ideal. I observed that though we are satisfied his doctrine is not true, it is impossible to refute it. I never shall forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it, - 'I refute it thus.' This was a stout exemplification of the first truths . . . or . . . original principles . . . without admitting which we can no more argue in metaphysics, than we can argue in mathematics without axioms. To me it is not conceivable how Berkeley can be answered by pure reasoning. Johnson portrays Berkeley as a philosopher hopelessly out of touch with human life; one aim of the present Companion is to supply a portrait of Berkeley that is more rounded and more just. The Berkeley of the essays that follow is not only an immaterialist philosopher, but a human being engaged - intellectually and often practically - with central issues in psychology, education, natural science, mathematics, economic development, ethics, politics, and religion, many of which are issues of continuing importance. Immaterialism is by no means neglected: Several chapters will help the reader decide whether Johnson was right to suggest that Berkeley's denial of matter is at odds with common sense and everyday experience, or whether Boswell was right to conclude that Berkeley cannot be refuted by reasoning.