The Troublesome Gray Area of Evaluation

Source: xkcd
It looks like I'm going to push this around for one more day.  Yesterday, following a conversation from Wednesday, I wondered aloud about what "good" beer is.  I invited comments and even the responses illustrate how difficult it is to consider the question. We can't discuss "good" until we agree about what the term means.  But let's step back even further--can we agree on what beer is?

The theory of criticism is not new to beer.  One of the more entertaining literary critics is Terry Eagleton, who gets existential on the nature of his subject of inquiry, literature:
There is no such thing as a literary work or tradition which is valuable in itself, regardless of what anyone might have said or come to say about it.  "Value" is a transitive term: it means whatever is valued by certain people in specific situations, according to particular criteria and in the light of given purposes.  It is thus quite possible that, given a deep enough transformation of our history, we may in the future produce a society which is unable to get anything at all out of Shakespeare.  [Literary Theory, 1983]
The idea of "literature" is like "good beer"--fiction exists, but literature, "good" fiction, is a subjective, collective construct.  Eagleton goes into an extremely detailed unpacking of this idea, reflecting on how deeply human experience and belief color our subjective evaluations.  He risks sliding into a theory of complete subjectivity--as did some of the "good beer" commenters--but pulls up short (and for the purposes of our discussion, substitute in your mind the words "good beer" when he writes "literature"):
If it will not do to see literature as an "objective" descriptive category, neither will it do to say that literature is just what people choose to call literature. 
Why?  Eagleton acknowledges that literature doesn't exist "in the sense that insects do," but that doesn't mean it doesn't exist.  We are plunged into a gray area where meaning cannot be measured by empirical means but not dismissed as purely subjective.  The meaning comes in our collective understanding and agreements about what good is.  Because our understanding and agreements (not to mention conditions) change, meaning changes.  What was good in 1962 may not be good now or in 2062.

I don't think this is actually as hard as some of the commenters believe.  We have a number of benchmarks that help us feel our way.  We don't judge beer in a vacuum--we judge it in context.  Style is a huge aid here--it's fine for a stout to be roasty but not a pilsner.  "Good" is relative to expectation.  We have agreements about what should and should not be in a beer based on style.  (Phenols, diacetyl, oxidation--off flavors--are wrong in every case except those in which they're not.)  Once you agree on the general broad contours, then you come to the gray area of aesthetics.  Is this beer "good" relative to style, expectation, and other beers?  Now we're diving into the deep waters of subjectivity.

In 1975, "good beer" did not exist in the United States.  We had bad beer and beer, but no one would have spent ten seconds defending a theory of aesthetics as it related to a can of Schlitz.  After craft brewing, we invented the idea of good.  All the momentum behind craft brewing rested on the idea that there was such a thing as good beer.  We talk about beer, spend $20 on a bottle of beer, write blogs and books about beer, and argue about beer because we all tacitly agree that "good beer" exists.  So to walk up to that line and say, "it's whatever you think it is" is, well, chicken. 

Until the past five years, when turnip-and-beet beers started to be greeted not with derisive laughter but serious interest and consideration, I felt I had a pretty good theory of "good beer."  I could tell you what it was and defend it.  But now we have, as a culture, begun to value beer differently.  When someone hands me a glass of beer brewed not to a standard style that has weird, unfamiliar ingredients in it, I find my theory bereft.  There is a way to evaluate the beer, but we haven't yet gotten to Eagleton's definition--"value means whatever is valued by certain people in specific situations, according to particular criteria and in the light of given purposes."

We don't actually have to write down the theory.  Literature does fine with out literary theory, and "good beer" will thrive without a blogger building the beautiful architecture of an aesthetic model.  I'm having more a crisis of confidence.  Presented with a weird beer, I wonder: is "liking" it enough?  Surely there's more to it.  But what?

But what?