Mathematics entered on its positive stage at quite an early period, chemistry and biology only in recent times, while, in the highest and most complicated science, the metaphysical (negative, liberal, democratic, revolutionary) mode of thought is still battling with the feudalism of the theological mode.  To make sociology positive is the mission of the second half of Comte’s work, and to this goal his philosophical activity had been directed from the beginning.  Comte rates the efforts of political economy very low, with the exception of the work of Adam Smith, and will not let them pass as a preparation for scientific sociology, holding that they are based on false abstractions.  Psychology, which is absent from the above enumeration, is to form a branch of biology, and exclusively to use the objective method, especially phrenology (to the three faculties of the soul, “heart, character, and intellect,” correspond three regions of the brain).  Self-observation, so Comte, making an impossibility out of a difficulty, teaches, can at most inform us concerning our feelings and passions, and not at all concerning our own thinking, since reflection brings to a stop the process to which it attends, and thus destroys its object.  The sole source of knowledge is external sense-perception.  In his Positive Polity Comte subsequently added a seventh fundamental science, ethics or anthropology.

Sociology,[1] the elevation of which to the rank of a positive science is the principal aim of our philosopher, uses the same method as the natural sciences, namely, the interrogation and interpretation of experience by means of induction and deduction, only that here the usual relation of these two instruments of knowledge is reversed.  Between inorganic and organic philosophy, both of which proceed from the known to the unknown, there is this difference, that in the former the advance is from the elements, as that which alone is directly accessible, to the whole which is composed of them, while in the latter the opposite is the case, since here the whole is better known than the individual parts of which it consists.  Hence, in inorganic science the laws of the composite phenomena are obtained by deduction (from the laws of the simple facts inductively discovered) and confirmed by observation; in sociology, on the other hand, the laws are found through (historical) experience, and deductively verified (from the nature of man as established by biology) only in the sequel.  Since the phenomena of society are determined not merely by the general laws of human nature, but, above all, by the growing influence of the past, historical studies must form the basis of sociological inquiry.

[Footnote 1:  Cf.  Krohn:  Beitraege zur Kenntniss und Wuerdigung der Soziologie, Jahrbuecher fuer Nationaloekonomie und Statistik, New Series, vols. i. and iii., 1880 and 1881.]