THE PRINCIPLES
OF
PSYCHOLOGY
BY
WILLIAM JAMES
PROFESSOR OF PSYCHOLOGY IN HARVARD UNIVERSITY
IN TWO VOLUMES
VOL. I
NEW YORK
HENRY HOLT AND COMPANY
1918
TO
MY DEAR FRIEND
FRANÇOIS PILLON.
AS A TOKEN OF AFFECTION,
AND AN ACKNOWLEDGMENT OF WHAT I OWE
TO THE
CRITIQUE PHILOSOPHIQUE.
PREFACE.
The treatise which follows has in the main grown up inconnection with the author's class-room instruction inPsychology, although it is true that some of the chaptersare more 'metaphysical,' and others fuller of detail, thanis suitable for students who are going over the subject forthe first time. The consequence of this is that, in spite ofthe exclusion of the important subjects of pleasure andpain, and moral and æsthetic feelings and judgments, thework has grown to a length which no one can regret morethan the writer himself. The man must indeed be sanguinewho, in this crowded age, can hope to have many readersfor fourteen hundred continuous pages from his pen. Butwer Vieles bringt wird Manchem etwas bringen; and, by judiciouslyskipping according to their several needs, I am surethat many sorts of readers, even those who are just beginningthe study of the subject, will find my book of use.Since the beginners are most in need of guidance, I suggestfor their behoof that they omit altogether on a firstreading chapters 6, 7, 8, 10 (from page 330 to page 371),12, 13, 15, 17, 20, 21, and 28. The better to awaken theneophyte's interest, it is possible that the wise order wouldbe to pass directly from chapter 4 to chapters 23, 24, 25,and 26, and thence to return to the first volume again.Chapter 20, on Space-perception, is a terrible thing, which,unless written with all that detail, could not be fairlytreated at all. An abridgment of it, called 'The SpatialQuale,' which appeared in the Journal of SpeculativePhilosophy, vol. xiii, p. 64, may be found by some personsa useful substitute for the entire chapter.
I have kept close to the point of view of natural sciencethroughout the book. Every natural science assumes certain[Pg vi]data uncritically, and declines to challenge the elementsbetween which its own 'laws' obtain, and fromwhich its own deductions are carried on. Psychology, thescience of finite individual minds, assumes as its data (1)thoughts and feelings, and (2) a physical world in time andspace with which they coexist and which (3) they know. Ofcourse these data themselves are discussable; but the discussionof them (as of other elements) is called metaphysicsand falls outside the province of this book. Thisbook, assuming that thoughts and feelings exist and arevehicles of knowledge, thereupon contends that psychologywhen she has ascertained the empirical correlation of thevarious sorts of thought or feeling with definite conditionsof the brain, can go no farther—can go no farther, that is,as a natural science. If she goes farther she becomesmetaphysical. All attempts to explain our phenomenallygiven thoughts as products of deeper-lying entities(whether the latter be named 'Soul,' 'TranscendentalEgo,' 'Ideas,' or 'Elementary Units of Consciousness') aremetaphysical. This book consequently rejects both theassociationist and the spiritualist theories; and in thisstrictly positivistic point of view consists the onl