Also, even finding an average feather is impossible with all the variation since the development of feathers (much of it uncertain in the fossil record), the difficulty of defining the first true feather, the fact that the sample size is dimishingly small over the age of the universe, and so on.
Perhaps it's the bias of my training, but rather than considering the feather as a physical phenomenon that is loosely defined and may or may not exist, I think it's more useful to consider the feather as a sociological phenomenon, a symbol or node of reference. We can't properly speak of the mass of a symbol, but we could consider the contexts, associations, and meanings associated with the appearance of the feather symbol and particularly the kinds of contexts in which the symbol can be expressed within a particular discourse community, all of which contribute to its weight. Necessarily, this would be unique to any particular social context, and no broad generalizations could be made across communities, since the feather as a sociological phenomenon is properly a characteristic of the society, rather than any transcending attribute of a proposed physical or formal "feather."
~ I know I shouldn't use tildes for decoration, but they always make me feel at home. ~