What meaning can be given to the notion "increase of life" as the end of conduct, without interpreting life in terms of pleasure? Can we, the question may be put, reach a "natural" good as distinct from "sensible good" or pleasure? We must discard at the outset any such "rational" view of nature as gave colour to the Stoic doctrine by identifying nature with the universal reason. And we must equally avoid the doctrine that reason regulative of conduct is manifested in the constitution of man either in a distinct faculty, such as "conscience," or in the due regulation of the various impulses. Trendelenburg's teleological conception of human nature, for instance, implies a rational element which could not be got from the causal sequence traced by evolution.[250] For he determines the essence of man by reference to the inner end of his constitution, and postulates an organic unity of impulses which, in the form of conscience, protests against self-seeking action on the part of any single impulse. But no other hierarchy of motives can be admitted here than that produced by the natural law of evolution; and this law can only show how one impulse, or class of impulses, has become more authoritative, by showing how it has become stronger or more persistent: the other methods of evolving this authority on the basis of naturalism, do so by means of the pleasurable or painful consequences of motives and actions. [Sidenote: either subjective or objective.] There are two ways in which, on most or all ethical theories, the attempt may be made to distinguish "good" from "bad" conduct. We may either look to a subjective motive or impulse as giving the means of distinction, or we may test conduct by its conformity with an objective standard. If we like to make use of the terms self-preservation and self-development, then these may refer either to the subjective impulse which urges man to preserve or develop his life, or to some objective standard for estimating actions according as they actually tend to prolong life or enrich it. Both these possibilities are open to the theory of evolution. Although the subjective impulse is, of course, a property of the individual, it may be the result of the whole course of social development, and thus take in others as well as self in the range of its application. It is therefore necessary to examine both methods of determination with some care, especially as we are in no little danger of reaching an illusory appearance of conclusiveness by allowing the subjective standard to rest on the objective, and the objective, in turn, on the subjective. [Sidenote: (_a_) Subjective standard: most persistent impulses;]