Who is a Jew?

Although I've given a lot of thought to this topic over the years, I'm not sure how far I've gotten with it.

I'm tempted to think of Jewishness as an essentially contested concept, whose meaning by its nature cannot be decisively fixed.  For OJs, you're Jewish if (a) you are born to a Jewish mother or (b) you convert under the guidance of regcognized OJ authorities.  For RJs, you're Jewish if (a) you are born to a Jewish mother or father and self-identify as Jewish or (b) you convert under the guidance of regcognized religious authorities of any stripe.  OJs, by and large, do not accept the authority of RJ rulings in this area, and RJs do not recognize OJs standing to render authoritative opnions on the matter of their own status.  OJs claim authenticity via adherence to halacha; RJs claim that adherence to halacha is not the only route to authenticity.

All of this is pretty well known.  As an RJ, I was raised believing that patrilineal descent was a sufficient cause of Jewishness and that anyone who said otherwise was being exclusive and exclusionary.  If someone was "Jewish enough" for Hitler, I remember learning, why shouldn't they be Jewish enough for the Jewish people, for the State of Israel, etc.  I had some friends in Sunday School and Hebrew School whose mothers weren't Jewish, but they had Bar and Bat Mitzvahs just the same.  It just never seemed to matter who "was" or "wasn't" a Jew.

After years of undergraduate and graduate education studing the socio-political and philosophical underpinnings of identity (not in the context of Judiasm per se), it seems to me rather obvious that there are many different "Jewishnesses" that overlap in socio-religious space, including:

1. self-identification:  if I say I'm a Jew, then I'm Jewish
2. social-identification: if consensus in my community says I'm a Jew, then I'm Jewish
3. technical identification: if my communitiy's authority figures say that I meet the requirements of being Jewish -- be they liberal or conservative -- then I'm Jewish
4. cultural identification:  if I'm raised by cultural Jews, then regardless of what I, they or others say, then I'm Jewish

The Torah says you're Jewish if you're born to a Jewish mother, but that's clearly just a technical identification only.  One could self identifty as Jewish, and behave accordingly, but live in a community where no one else recognized your technical identification as Jewish.  One could be born and raised as a Jew, but eventually stop thinking of one's self as Jewish.  In each case, there could be arguments made on each side, but there is no earthly neutral arbiter to say which is "right."  Replace "Jewish" with "American" or "Native American" or "socialist" or what have you and the point is the same:  When it comes to identity, no one gets to definitively call the shots.

Well, at least that what the liberal RJ in me says.

The problem I find, in the end, is that this explanation is unsatisfying...but I'm not sure exactly how to express it.  If it is enough to say one is Jewish to be Jewish, then what are the possibilities (or lack thereof) for that Jewishness?  How much consensus is needed?  What justificaitons are needed?  What explanations are required? 

RJ says patrilineal descent counts; halacha says it doesn't.  In a sense, of course, this only concerns the technical identification, i.e., the decision-rules for determining who will and will not be counted as Jewish.  As an RJ, as a liberal thinker, I recoil from the patriarchy of halacha; but, then, does "adding in" patrilineal descent make things right, or does it fundamentally subscribe to the underlying illiberal logic inherent in matrilineal-only descent?  That is, if we decide who "is" or "isn't" a Jew based, in the first instance, on one's parents, isn't that at odds with the allegedly liberal underpinnings of RJ, that the rules need to change with the times?  This is my confusion:  If you reject halacha as a basis for law, then what do you have?  The problem, of course, is that halacha has no room for amendment, only for addition.  It's a fundamentally ossified document.  The American Constitution provides a good counterpoint:  There is nothing in the document that can't be changed by sufficient consensus, either by amendment or the accretion of precedent.  If we wanted to, we could amend away the right to free speech, religion, etc. -- the very things we say are fundamental to being American.  Halacha offers no such process.  We don't get to vote, and consensus is fashioned in a highly exclusionary way. 

But isn't that the way all religions work?