Recent reports that the American Jewish population is well over 6 million have been taken far too seriously, writes demographer Pini Herman:

With all the pronouncements about the newly found million Jews we don’t know anything more about one single Jew in the US than we did before this “PEGGING” of US Jews at the over 6.4 million mark rather than the previous 5.2 million which would have made Israel at 5.8 million Jews the largest Jewish population in the world.

It all hinges on how hundreds of thousands of US respondents answered the generic religion survey question on dozens of general surveys in the US and whether Jewish screening questions were properly applied in more specialized Jewish population studies.

One problem with a simple survey question, Dr. Herman notes, is " false positives, that is non-Jews claiming to be Jewish". A high likely rate of false positives, he argues, renders the claim that American Jewry is now larger than Israeli Jewry nothing more than a "Jewish demographic castle in the air".

While an Israel-Diaspora horse race is always fun sport, I am much more interested in an implicit problem underlying (and, to my mind, undermining) this entire discussion. Namely: what is a false positive, and what definition makes that determination?

It's easy enough  to think of a person who might strike you (and me, and every Jew we know) as a clear false positive. There do exist, for example, Christians with no Jewish ancestry who nonetheless call themselves Jews, taking the traditional Christian doctrine that, since Jesus, the church is the new people of Israel a little more literally than most Christians do.

My assertion that such people are not really Jews is, however, entirely subjective -- as is Dr. Herman's implicit assertion that there is even such a thing as a false positive. After all, there are many possible definitions of Jewishness, and one of them might well be that anyone who claims to be Jewish is Jewish, by virtue of claiming so. This definition would admit our over-literal Christians, as well as Messianic Jews, as well as anyone with a Jewish fourth-cousin-in-law who wants to identify as Jewish, as well as anyone else who wants to jump instantly on the bandwagon for any reason at all, with no requirements of any kind.

I think most Jews would find this definition too permissive, and I certainly join them. Indeed, my personal views of the definition of Jewishness follow my personal devotion to the Modern Orthodox type of interpretation of halakhah -- which means I personally find the definition(s) used by the Reform movement far too permissive as well. Yet most of America's Reform Jews (who far outnumber the American Orthodox) would strongly disagree with me. My point is that it is impossible to count Jews in any context without first defining Jewishness, and defining Jewishness is an issue upon which the Jewish community as a whole is vehemently and painfully splintered.

What can be said, then, of an argument between some scholars counting 5.2 million Jews and others counting 6.5, when all five-or-six-million Jews are in the middle of a massive argument about what it means to belong to the group being counted? I'm sure each of the research teams in question used precise definitions, and I imagine in this era of sophisticated social science the definitions used in various different studies most often match one another. But since no one definition can command anything even close to consensus among the Jewish people, of how much value is all the precision?

5.2 million Jews... 6.5 million Jews... Maybe if we could agree about the definition of one Jew, the rest would be a little bit easier.

(See also: the October 2010 issue of Sh'ma, focusing on "Counting Jews" and our August 2011 newsletter, focusing on the Jewish Population.)