Marx considered his work to be scientific, based on economics and history, and Durkheim considered his to be scientific, based on an ordered analysis of the moral issues underlying the division of labor. Both Marx and Durkheim began where all truly scientific inquiry must begin--at the beginning. Durkheim writes:
What reconciles science and morality is the science of morality, for at the same time as it teaches us toi respect moral reality it affords us the means of improving it. . . . Here as elsewhere, science presupposes the entire freedom of the mind. we must rid ourselves of those ways of perceiving and judging that long habit has implanted in us (Durkheim Division xxviii-xxix).
Durkheim does not question the existence of moral realuity, but he does begin with a questioning of everything which has been assumed to describe and analyze it previously.
Marx similarly advocates a starting from the beginning, a tearing down of what has come before:
And the socialist principle itself represents, on the whole, onky one side, affecvting the reality of the true human essence. we have to concern ourselves just as much with the other side, the theoretical existence of man, in other words to make religion, science, etc., the objects of ouyr criticism (Marx 13).
The latter excerpt is from a piece called "For a Ruthless Criticism of Everything Existing."
Both Marx and Durkheim follow the basic processes of scientific inquiry by questioning the very foundation of their subjects, and then use the same questioning method to establish their arguments about society.
In particular, it will be seen how we have studied social solidarity through the system of juridical rules, how in the search for causes, we have laid aside everything that too readily lends itself to personal judgments and subjecvtive appraisal--this so as to penetrate certain facts of social structure profound enough to be objects of the understanding, and cons...