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Rich conversation about both classification in general and calling things alive in particular in class this morning.  Thanks to all.  A few thoughts that stuck in my mind ...

Understanding is always subjective, in two senses.  One is that we always make sense of things from a particular point of view.  The other, as per David, is that understanding is always relative to some objective, ie is good for something.  At the same time, we don't want to get into the "anything goes" problem.  We'd like to have some common understandings so we can share things/work together.  Maybe that's what we mean by "objective," shared commonalities in our individual inevitably "subjective" understandings?  For more along these lines, see "The objectivity/subjectivity spectrum: having one's cake and eating it too?"  "Objective" understandings are derived from individual subjective ones, and involve agreements on what purpose shared understandings are meant to serve?

All this is quite general, not at all specific to biology or the problem of defining life.  The "classification" or naming issue is relevant in a whole host of contexts, including several current ones.  See class notes for today for links to a number of conversations relevant in this context. 

So, what is a living organism?  It, like what is a man and what is a woman, depends on what collection of subjectivities we're bringing together and  what common objective we want to work on together.  Is religion, and the concept of a soul, relevant?  Of course, but if we're looking for a common understanding among people in the class, or among some wider group of humans, neither it nor the concept of a "life essence" of any kind, serve the need for a common understanding that motivates further questions about living organisms. Maybe the definition we're working on serves that need?  We'll see.