A Treatise Concerning the Principles of Human Knowledge

Berkeley begins by reflecting on the nature of philosophy itself, which is “nothing else but the study of wisdom and truth” (5). The paradox of philosophy is that the search for wisdom does not lead to “a greater calm and serenity of mind” (5).. Those who make the effort to pursue philosophy open their minds to all kinds of difficulties, including what Berkeley considers the pitfall of Skepticism (see Index of Terms for more discussion). By contrast, non-philosophers, those who “walk the high road of plain common sense” (5), are in no such danger; they understand the world as they perceive it through their senses and experiences, without troubling themselves with intellectual complexities.

Berkeley rejects the idea that the existence of intellectual difficulties is rooted in a natural “obscurity of things” (5). If God has planted a natural desire for knowledge and wisdom in our souls, it must mean that knowledge and wisdom are within our reach. Berkeley states his opinion that philosophers themselves are responsible for most philosophical difficulties: “we have first raised a dust and then complain we cannot see” (6). As a Theist and Christian, Berkeley is convinced that there is order in the universe, rooted in the nature of God, and that human beings can discover this order.

This leads Berkeley to state his main purpose: to remove the obstacles that some philosophers have placed in the way of truth, obstacles that lead to extreme skeptical doubt. The Treatise will outline “the first principles of human knowledge” (6) and expose those “false principles” that lead one astray. The book will be written partly against the background of, and as a critique of, some of the prevailing thought of Berkeley’s day. In contrast to some earlier books of philosophy which were large in scope, the Treatise will be a “close and narrow survey” (7) and, as such, it may succeed in revealing truths that have escaped other thinkers.

Berkeley announces that his discussion will center on “the abuse of language” (7) as a source of confusion and error in philosophy. Such abuse has led many people to believe that we have the “power of framing abstract ideas” (7), a notion which Berkeley rejects.

Empiricists assert that our minds have the power to form abstract ideas of qualities that we perceive in objects. For example, from seeing a red apple we might form an abstract idea of “red” or “redness;” from there, we might form further abstract concepts of “color,” “shape,” and so forth. In this view, the mind forms a general idea of a quality that is common to many different things; this general idea is an abstraction independent of how the quality exists in a particular object. One commonly used abstraction is the idea of “humanity” or “human nature,” which includes all the qualities common to human beings.

Berkeley professes that the mind cannot form abstract concepts in this way. He is unable to think of “color” or “motion” without thinking of a particular color or a particular movement. He challenges readers to try to form a mental image of abstract concepts—such as an ideal triangle—and see if they too, like him, are able to think only in particulars (such as an isosceles triangle). Berkeley believes that most people are like this, and that the ability to conceive “abstract notions” is possessed, if at all, only by “the learned.” Indeed, this very fact disproves John Locke’s thesis that what separates humans from animals is the ability to think abstractly (11).

Although we can conceive of different things that have a common quality or property (thus conceiving of a general idea), we cannot, properly speaking, conceive of an abstract idea. Instead, we conceive only particulars: a tall man, a red apple, etc.

It is mostly our use of language that leads us to believe we can conceive of abstract ideas. Language preconditions us to validate certain ideas, by raising certain feelings or reactions in us at the mention of certain words or concepts. Thus, a certain relationship is established between words and ideas, which habit solidifies. The wise thinker should seek to free himself from being imposed upon by the “delusion of words,” which “so much contribute to blind the judgment” (22).

In the Introduction, Berkeley invites his readers to think along with him, testing what he says against their own perceptions and intuitions. He models the kind of thinking in which he wants his readers to engage and presents his Treatise as a process of “looking into your own thoughts” (33) to check whether Berkeley’s claims make sense. Berkeley’s philosophical approach differs from one that would enjoin the reader to accept all the claims made by the author unquestioningly on the basis of the author’s authority. For Berkeley, the testing process he proposes is a reliable safeguard against error: “so long as I confine my thoughts to my own ideas divested of words, I do not see how I can easily be mistaken” (21). It is also a way to anticipate and, hopefully, allay objections to his ideas, which challenge concepts that readers have accepted as common knowledge.