How "Man" is Like a Watch

One of the more interesting points (so far) in Alasdair MacIntyre's "After Virtue" is the idea that since the Aristotelian concept of the world was displaced by the modern view, "Man" has ceased to be a "Functional concept".

MacIntyre uses a watch as an example.  A watch has attached with it a functional concept.  It is expected to do something (tell time).  The definition of 'watch' is both a definition of it as an object and its function.  A good watch is a watch that functions according to its criteria for being a watch.

"Man" needs to have a similar "functional concept":
To be a man is to fill a set of roles each of which has its own point and purpose: member of a family, citizen, soldier, philosopher, servant of God.  It is only when man is thought of as an individual prior to and apart from all roles that 'man' ceases to be a functional concept.
MacIntyre argues that in order for moral arguments to come from anywhere other than personal preference there needs to be a functional concept of 'man'.  In fact, in calling someone 'good' implies that there is a function and purpose that he/she is fulfilling (just like a 'good' watch).  'Man' needs to have a purpose or telos so that he/she can work out not only where they are but also where they need to be.  Without this functional concept morality falls into circularity and emotivism.