But what the theory of evolution has to determine with regard to moral intuitions or sensibilities would seem to be not so much their ethical validity or invalidity, as the range and manner of their ethical application. It attempts to show that particular moral beliefs or feelings have been originated and formed by certain external customs belonging to the conditions of social or family life. These customs have impressed themselves upon the mental structure, and reappear in the individual in the shape of organic tendencies to certain actions, or classes of actions, and of aversion to other actions, accompanied by a corresponding mental sentiment--or judgment--of approbation or disapprobation. Thus the individual comes instinctively to feel--or to judge,--"A ought to be done," "B ought not to be done." Now the evolutionist, as I conceive, does not proceed to infer that such judgments are invalid because he has shown how they originated--does not conclude (to use Mr Sidgwick's words) that "_all_ propositions of the form 'X is right' or 'good,' are untrustworthy;" but he does ask in what way the history of these judgments affects their application.[117] [Sidenote: (_a_) different social conditions from which they may have resulted,] (_a_) He recognises, in the first place, that all such judgments are the natural result of a certain social condition, and that there is, therefore, some probability that the same kind of social state could not continue to exist were those moral judgments habitually disregarded in conduct. They have resulted from a certain state of society, and have been assumed--after insufficient experience, perhaps--to be required for the stability of that state, so that every action opposed to these moral judgments will probably tend to weaken social bonds. But the evolutionist's conclusions are not restricted to such generalities. He may show that certain moral judgments or sentiments have had their origin from the habits of union between individuals, and of respect for the rights of property, which have obtained in every relatively permanent society, and which may therefore be inferred to be probably necessary for the continued existence of any community; that certain other sentiments or intuitions have descended to present individuals from customs which have not been so universal in the history of societies, although the communities possessing them have shown greater power of vitality than those in which they were absent; while others, again, may be traced to institutions which, from their occasional and unprogressive character, may be shown to be neither necessary nor beneficial. [Sidenote: and consequent difference in their value for conduct;]