E.O. Wilson in Consilience: The Unity of Knowledge:

The current status of the social sciences can be put in perspective by comparing them with the medical sciences.  Both have been entrusted with big, urgent problems.  …  In both spheres the problems have been intractably complex, partly because the root causes are poorly understood.

The medical sciences are nevertheless progressing dramatically …

There is also progress in the social sciences, but it is much slower, and not at all animated by the same information flow and optimistic spirit.  Cooperation is sluggish at best; even genuine discoveries are often obscured by bitter ideological disputes …

The crucial difference between the two domains is consilience: The medical sciences have it and the social sciences do not.  Medical scientists build upon a coherent foundation of molecular and cell biology. They pursue elements of health and illness all the way down to the level of biophysical chemistry …

Social scientists, like medical scientists, have a vast store of factual information and an arsenal of sophisticated statistical techniques for its analysis.  They are intellectually capable.  Many of their leading thinkers will tell you, if asked, that all is well, that the disciplines are on track – sort of, more or less.  Still it is obvious to even casual inspection that the efforts of social scientists are snarled by disunity and a failure of vision.  And the reasons for the confusion are becoming increasingly clear.  Social scientists by and large spurn the idea of the hierarchical ordering of knowledge that unites and drives the natural sciences.