Nomothetic and Idiographic

There is a nice post on Shrinkette (I love that name) that contains an excerpt from an interview with Nancy Andreasen, MD.  The original was published in New Scientist, in their subscription-only section.  There is a lot one could say about the material, but I am going to focus on one little bit:

There is less emphasis on careful observation. The fundamental point is that the individual patient and his or her uniqueness should form the centrepiece of clinical practice...There is an increased tendency to make diagnosis through checklists, with less emphasis on the interesting uniqueness of each individual patient and on the humanism that lay at the heart of early psychiatry.

Obviously I agree with the proposition that there should be a strong emphasis on observation (observations are gold...), but I think the statement about emphasis on "the interesting uniqueness of each individual patient"  deserves some clarification.

There are two different perspectives that one can use to understand a person within the context of a social system: the nomothetic, and the idiographic.  See the blurb from Encyclopædia Britannica for an explanation of those two terms.  Or read this, which is from a paper I wrote 14.5 years ago:

When I evaluate people, I try to collect two kinds of information in order to answer two conceptual questions about the client.  The first thing I want to know is: "What features does this client have in common with other, similar clients?"  The  (nomothetic) information needed to answer this question is objective and descriptive in nature.  It allows you to compare the client to the population in general, as well as to the subpopulations of people with similar difficulties.  The second question I want to answer is: "What makes this client different from everyone else?"  The (idiographic) information needed to answer this question is personal, individual, historical, and may even be subjective. 

It is not that one perspective is better than another; rather, the point is that there are two perspectives and each has the potential to reveal things that the other does not.