Last Friday, Jen Miller posted her thoughts about The Time Traveler's Wife and how it relates to the fantasy genre. Here, Ken Schneyer responds to that post with his own thoughts about the validity of genre.
Four hundred years ago, Shakespeare showed us the fluidity of genre boundaries by writing plays that deliberately messed with Aristotle's definitions of tragedy and comedy. Compare Othello to Much Ado About Nothing, or take different scenes from Measure for Measure out of context, and you'll see what I mean.
Nonetheless, people persist in believing in genres, and in assigning different characteristics to them as if they were natural and even immutable. Sometimes it's something as silly as blanket attributions of quality (e.g., the ones we've seen over and over again, "It can't be science fiction; it's too good", or "Nobody ever wrote a romance as serious literature except Jane Austen", etc.). Sometimes it's an attempt to define different subgenres (e.g., Are time travel stories science fiction because they involve the logical consequences of a particular theory, or are they fantasy because they're impossible?). Sometimes it's a fight over which shelf the book will occupy in the bookstore (hence Margaret Atwood's insistence that her novels aren't SF, and people's perplexity as to whether The Time Traveler's Wife belongs with romance, literature or SF).