§1. In the preceding chapter we have seen reason to conclude that, while obedience to recognised rules of duty tends, under ordinary circumstances, to promote the happiness of the agent, there are yet no adequate empirical grounds for regarding the performance of duty as a universal or infallible means to the attainment of this end. Even, however, if it were otherwise, even if it were demonstrably reasonable for the egoist to choose duty at all costs under all circumstances, the systematic endeavour to realise this principle would not---according to common notions of morality---solve or supersede the problem of determining the right method for seeking happiness. For the received moral code allows within limits the pursuit of our own happiness, and even seems to regard it as morally prescribed; and still more emphatically inculcates the promotion of the happiness of other individuals, with whom we are in various ways specially connected: so that, under either head, the questions that we have before considered as to the determination and measurement of the elements of happiness would still require some kind of answer.
It remains to ask how far a scientific investigation of the causes of pleasure and pain can assist us in dealing with this practical problem.
Now it is obvious that for deciding which of two courses of action is preferable on hedonistic grounds, we require not only to measure pains and pleasures of different kinds, but also to ascertain how they may be produced or averted. In most important prudential decisions, complex chains of consequences are foreseen as intervening between the volition we are immediately to initiate and the feelings which constitute the ultimate end of our efforts; and the degree of accuracy with which we forecast each link of these chains obviously depends upon our knowledge, implicit or explicit, of the relations of cause and effect among various natural phenomena. But if we suppose the diflerent elements and immediate sources of happiness to have been duly ascertained and valued, the investigation of the conditions of production of each hardly belongs to a general treatise on the method of ethics but rather to some one or other of the special arts subordinate to the general art of conduct. Of these subordinate arts some have a more or less scientific basis, while others are in a merely empirical stage; thus if we have decided how far health is to be sought, it belongs to the systematic art of hygiene, based on physiological science, to furnish a detailed plan of seeking it; so far, on the other hand, as we aim at power or wealth or domestic happiness, such instruction as the experience of others can give will be chiefly obtained in an unsystematic form, either from advice relative to our own special circumstances, or from accounts of success and failure in analogous situations. In either me the exposition of such special arts does not appear to come within the scope of the present treatise; nor could it help us in dealing with the difficulties of measuring pleasures and pains which we have considered in the previous chapters.
It may, however, be thought that a knowledge of the causes of pleasure and pain may carry us beyond the determination of the means of gaining particular kinds of pleasure and avoiding particular kinds of pain; and enable us to substitute some deductive method of evaluing the elements of happiness for the empirical-reflective method of which we have seen the defects.
A hedonistic method, indeed, that would dispense altogether with direct estimates of the pleasurable and painful consequences of actions is almost as inconceivable as a method of astronomy that would dispense with observations of the stars. It is, however, conceivable that by induction from cases in which empirical measurement is easy we may obtain generalisations that will give us more trustworthy guidance than such measurement can do in complicated cases; we may be able to ascertain some general psychical or physical concomitant or antecedent of pleasure and pain, more easy to recognise, foresee, measure, and produce or avert in such cases, than pleasure and pain themselves. I am willing to hope that this refuge from the difficulties of Empirical Hedonism may some time or other be open to us: but I cannot perceive that it is at present available. There is at present, so far as I can judge, no satisfactorily established general theory of the causes of pleasure and pain; and such theories as have gained a certain degree of acceptance, as partially true or probable, are manifestly not adapted for the practical application that we here require.
The chief difficulty of finding a universally applicable theory of the causes of pleasures and pains is easily explained. Pleasures and pains may be assumed to have universally---like other psychical facts---certain cerebral nerve-processes, specifically unknown, as their inseparable concomitants: accordingly, we may seek their causes either in antecedent physical or antecedent psychical facts. But in one important class of cases the chief cognisable antecedents are obviously of the former kind, while in another important class they are obviously of the latter kind: the difficulty is to establish any theory equally applicable to both classes, or to bring the results of the two lines of inquiry under a single generalisation without palpably unsupported hypotheses. In the case of pleasures and pains---especially pains---connected with sensation the most important cognisable antecedents are clearly physical. I do not deny that, when the pain is foreseen, the attitude of mind in which it is met may materially influence its magnitude: indeed, in the hypnotic condition of the brain, the feeling of pain may be apparently altogether prevented by an antecedent belief that it will not be felt. Still in the main, under ordinary conditions, the pains of sensation---probably the intensest in the experience of most persons---invade and interrupt our psychical life from without; and it would be idle to look for the chief causes of their intensity or quality among antecedent psychical facts. This is not equally true of the most prominent pleasures of sense: since antecedent desire, if not an absolutely indispensable condition of such pleasures, seems at any rate necessary to their attaining a high degree of intensity. Still the chief causes of these desires themselves are clearly physical states and processes---not merely neural---in the organism of the sentient individual: and this is also true of a more indefinite kind of pleasure, which is an important element of ordinary human happiness,---the ``well-feeling'' that accompanies and is a sign of physical well-being.
On the other hand, when we investigate the causes of the pleasures and pains that belong to intellectual exercises or the play of personal affections,---or of the pleasures (and to some extent pains) that belong to the contemplation of beauty (or its opposite) in art or nature,---no physiological theory can carry us far, owing to our ignorance of the neural processes that accompany or antecede these feelings.
This is my general conclusion: the grounds for which I propose to illustrate and explain further in the present chapter. It would, however, seem to be quite beyond my limits to attempt anything like an exhaustive discussion of either psychological or physiological theories of the causes of pleasure and pain. I shall confine myself to certain leading generalisations, which seem to have a special interest for students of ethics; either because ethical motives have had a share in causing their acceptance; or because---though inadequately grounded as general theories---they appear to have a partial and limited value for practical guidance.