Della Pergola explained the background:
"In 2001, the Union of Jewish Communities sponsored a very large national survey, called the National Jewish Population Survey (NJPS). It was done by phone and using the most modern techniques available to find a small minority such as the Jews within a large country like the U.S. Of course, every survey has its limitations and is not exact; but the central finding was 5.2 or 5.3 million Jews in the United States."
He acknowledged that the broad definition of "Jewish" that was used was not exactly Halakhic [Jewish-legal], but rather included all those who define themselves as Jewish, or those who grew up as Jews and do not now profess another mono-theistic religion. Della Pergola said there are another 1.5 million Jews who said they were once Jewish but now consider themselves Christians or the like.
"The problem was," Della Pergola said, "that the 2001 figure was about 3-400,000 lower than expected. This was because of a 1990 survey that showed about 5.5 million, and in addition, we knew that there had been Jewish immigration to the U.S. in the 1990's - so it was felt that the number should have grown. The NJPS total was therefore accepted with some controversy. On the other hand, another study headed by the noted and unfortunately recently-deceased Egon Mayer of New York University also found 5.3 million Jews. So you have two independent studies, carried out by top people, coming up with similar results."
Amidst murmurs of dissent at the low findings for American Jewry, things came to a head when two respected demographers recently compiled local surveys from around the country, coming up with the figure of no fewer than 6.4 million U.S. Jews. This figure was published in the latest edition of the American Jewish Year Book.
Della Pergola acknowledges that the two researchers, Iran Sheskin of the University of Miami and Arnold Dashefsky of the University of Connecticut, are "respected academics... but is this an acceptable method of obtaining a total? One issue is that some of those found to be Jews are not the result of research in the field or interviews, but rather based on the word of a local informant who estimates how many Jews there are in his city. The value of this is very low; it is not research, but opinion. In addition, many of the surveys on which the study is based were done in different years, with different methodologies, and with different definitions; some include non-Jewish relatives, some don’t, etc. If you interview someone, say, in Philadelphia in 1988, and then call someone in Tucson in 1998, it's likely that there will be a fair amount of double-counting, because of the enormous amount of mobility in the United States... The only way to do it is to have one methodology, one definition, and within the shortest time span possible, as was done by the NJPS."
In the final analysis, what difference does it make if there are 5.2 million Jews or 6.4 million? Della Pergola says, "The issue is much more than mere demographics. It means that, for the first time, there are more core Jews in Israel than in the United States. This is, of course, big news, with broad ramifications, and I feel that there are certain circles within world Jewry who simply cannot cope with this notion. They think it's outrageous."
But Della Pergola is not discouraged: "Even if we don't agree now, within a few years, we will all see that this is true, as the Israeli Jewish population is growing, while elsewhere it is decreasing or remaining the same... This doesn't mean that Israel should be receiving more resources and funding from world Jewry, but rather the opposite: Israel must take more responsibility, give more, and be aware that the bigger brother has to help the smaller one; there must be a shift of resources, and Israel must be aware that it will have to give more and receive less."
The halakhic ramifications are also quite significant. If Israel now holds the largest Jewish population in the world, it is only a matter of years until the majority of world Jewry lives in Israel. A study done at the Institute of Contemporary Jewry at Hebrew University concluded that this will happen by the year 2030 - and others say it will occur sooner. Many Biblical commandments that applied only when the majority of Jews live in their Land might once again be totally binding. These include Jubilee, the Seventh Year, Tithes, Challah and more.
In a related issue, Arutz-7's Hillel Fendel asked Della Pergola his opinion on a seemingly fantastic find by the National Jewish Population Survey. In Feb. 2004, the NJPS found that among the 587,000 people raised as Orthodox Jews, nearly 60% are no longer Orthodox - in contrast with clearly dynamic and growing Orthodox and hareidi communities in many parts of the country.
Della Pergola said that the find is not as shocking as it might seem: "These numbers do not mirror only today's Orthodoxy, but also the Orthodoxy of the 1930s and 1940s when many Orthodox Jews, children of new immigrants and the like, became Conservative or Reform. Random Jews today are likely to have grown up several decade ago in an Orthodox home, but are today not Orthodox."
Orthodox Jewry is clearly growing at a fast pace, he said: "At present, Orthodox Jews make up roughly 10% of US Jewry, compared with about 25% who consider themselves unaffiliated. But of course, among children, it is very likely that the proportion of Orthodox Jews is not 10%, but much closer to 20%. The Orthodox are growing, while the others are not..."
A study released last May by the American Jewish Committee showed that Orthodox Judaism is growing in popularity among under-30 Jews in the U.S. Some 16% of Jews aged 18-29 identify themselves as Orthodox, the study revealed.