There are several recognised ways of treating this subject, none of which I have thought it desirable to adopt. We may start with existing systems, and either study them historically, tracing the changes in thought through the centuries, or compare and classify them according to relations of resemblance, or criticise their internal coherence. Or we may seek to add to the number of these systems: and claim after so many unsuccessful efforts to have at last attained the one true theory of the subject, by which all others may be tested. The present book contains neither the exposition of a system nor a natural or critical history of systems. I have attempted to define and unfold not one Method of Ethics, but several: at the same time these are not here studied historically, as methods that have actually been used or proposed for the regulation of practice; but rather as alternatives between which--so far as they cannot be reconciled--the human mind seems to me necessarily forced to choose, when it attempts to frame a complete synthesis of practical maxims and to act in a perfectly consistent manner. Thus, they might perhaps be called natural methods rationalised; because men commonly seem to guide themselves by a mixture of different methods, more or less disguised under ambiguities of language. The impulses or principles from which the different methods take their rise, the different claims of different ends to be rational, are admitted, to some extent, by all minds: and as along with these claims is felt the need of harmonising them--since it is, as was said, a postulate of the Practical Reason, that two conflicting rules of action cannot both be reasonable--the result is ordinarily either a confused blending, or a forced and premature reconciliation, of different principles and methods. Nor have the systems framed by professed moralists been free from similar defects. The writers have usually proceeded to synthesis without adequate analysis; the practical demand for the former being more urgently felt than the theoretical need of the latter. For here as in other points the development of the theory of Ethics would seem to be somewhat impeded by the preponderance of practical considerations; and perhaps a more complete detachment of the theoretical study of right conduct from its practical application is to be desired for the sake even of the latter itself: since a treatment which is a compound between the scientific and the hortatory is apt to miss both the results that it would combine; the mixture is bewildering to the brain and not stimulating to the heart. So again, I am inclined to think that here, as in other sciences, it would be an advantage to draw as distinct a line as possible between the known and the unknown; as the clear indication of an unsolved problem is at any rate a step to its solution. In ethical treatises, however, there has been a continual tendency to ignore and keep out of sight the difficulties of the subject; either unconsciously, from a latent conviction that the questions which the writer cannot answer satisfactorily must be questions which ought not to be asked; or consciously, that he may not shake the sway of morality over the minds of his readers. This last well-meant precaution frequently defeats itself: the difficulties thus concealed in exposition are liable to reappear in controversy: and then they appear not carefully limited, but magnified for polemical purposes. Thus we get on the one hand vague and hazy reconciliation, on the other loose and random exaggeration of discrepancies; and neither process is effective to dispel the original vagueness and ambiguity which lurks in the fundamental notions of our common practical reasonings. To eliminate or reduce this indefiniteness and confusion is the sole immediate end that I have proposed to myself in the present work. In order better to execute this task, I have refrained from expressly attempting any such complete and final solution of the chief ethical difficulties and controversies as would convert this exposition of various methods into the development of a harmonious system. At the same time I hope to afford aid towards the construction of such a system; because it seems easier to judge of the mutual relations and conflicting claims of different modes of thought, after an impartial and rigorous investigation of the conclusions to which they logically lead. It is not uncommon to find in reflecting on practical principles, that--however unhesitatingly they seem to command our assent at first sight, and however familiar and apparently clear the notions of which they are composed--nevertheless when we have carefully examined the consequences of adopting them they wear a changed and somewhat dubious aspect.