The number of Jews in the USA is probably neither the most important nor the most exciting detail in the vast research effort aimed at unveiling the deeper currents contextualizing life and meaning in the largest Jewish community worldwide (outside of Israel). Differences of opinion regarding the numerical size of US Jewry, however, is the subject of debate and engaging in constructive dialog about it should hopefully enrich the whole community of data providers and users.

In their review (Tighe et al. 2022) of the Pew Research Center’s (PRC) estimate of 7.5 million Jewish Americans for 2020 (Pew Research Center 2021), the authors—all distinguished current or past members of Brandeis University’s Cohen Research Center for Modern Jewish Studies—make a number of affirmations, which I wholeheartedly support. Among grounds for agreement I concur that “with the majority of US Jewish adults identifying by religion, these [the PRC] data are highly useful;” in some instances [speaking of the 2000/01National Jewish Population Survey NJPS] “while analyses of the relationships among measures in [a] survey were potentially valuable, the population estimates could not be considered reliable;” and “demographic facts will not shape the future of the American Jewish community,” whose “future will be [also] shaped by a host of endogenous and exogenous factors.” We are in agreement that the social scientific study of contemporary Jewry can benefit from the use of quantitative tools, and in fact we share a propensity to intensively use those tools, although we do that somewhat differently. We certainly agree that Jewish population estimates cannot be taken as an exact science, but rather constitute important points within a theoretically probable range. The very unequal quality of the data, the uncertain reliability of samples, the definitional predicament, and other technical and substantive factors generate what I have defined as the permanently provisional nature of Jewish population estimates (DellaPergola 2022, 313).

We ultimately are in agreement that the empirical findings of our research should not remain confined to academic debate, but should be carefully interrogated to improve both our understanding of Jewish communities in the USA and the quality of a broad range of community opportunities offered to stakeholders. The rich information we can extract from numbers provides demographers, sociologists, and historians matter for speculation and analytic work. Perhaps more importantly, it offers essential information for policy-oriented reflections and action by community leaders, educators, and social workers.

There are, however, also important points of dissent among us. In the first place, Tighe et al. (2022) make it clear that in their view the PRC survey’s “conclusions about a growing US Jewish population suggest a new narrative [my italics] of American Jewish life that reflects the diversity of ways in which Jewish identity is expressed.” Here we come to a central bone of contention: are we primarily dealing with Jewish community narratives, or with the social scientific study of Jewish population and society? Is our main concern with a theoretical–empirical approach through whose lens or lenses we may try to ascertain and interpret facts, their determinants and consequences—leaving the normative debate to a later stage? Or do we rather focus on the individually or collectively perceived normative significance of the findings—intermingling Jewish corporate discourse with the data, and mediated by particular institutional interests? And as a corollary, is there only one possible type of Jewish community discourse, or are there several, with different potential goals and target constituencies? Is the narrative, for example, of the Orthodox Union the same as that of the Union of Reform Judaism? And independently of the previous question, is “the lack of the bravery ([or inclination] or interest) to concede that one is just Jewish” (DellaPergola 2022, 361) one of the manifestations of “an American Jewish life that reflects the diversity of ways in which Jewish identity is expressed” (Tighe et al. 2022)?

Another big bone of contention, significantly related to the previous one, is the assertion by Tighe et al. (2022) that there exists “substantial consensus among social scientists who study Jewish populations” about which populations should be surveyed and which portions of them should be included in a definition of the Jewish population. Such an affirmation implies that research strives at reaching unanimity, that dissenting voices are not legitimate or at least not welcome and that a field can aspire for hegemony over diverse knowledge outputs—not unlike the late Soviet Academy of Sciences. I find this stance extremely reductive considering the rich amount of wisdom and creativity that pervades the wide and diverse public of interested practitioners and readers.

Prof. Dan Shechtman of the Technion was awarded the 2011 Nobel Prize in Chemistry for the discovery of quasicrystals, making him one of six Israelis who have won the Nobel Prize in Chemistry. He is an interesting example of a scientist going against consensus. Shechtman was opposed and even ridiculed for decades, including by some of the leading experts in his field worldwide, for holding an idea that was considered wrong or impossible. He was eventually proven right. This example from chemistry may not be entirely relevant in the social sciences, which are a softer type of discipline. Each discipline, with its underlying logic and tools, can critically use its relative advantage over others to advance knowledge. And progress often relies on dissenting voices, who raise the possibility of alternative ways of thinking.

Related to this is the now untenable assertion that there is one and only one way to define Jewish populations in a binary world of Jews and non-Jews (DellaPergola 2015). While this may be still true at the normative-legal level, namely by the Jewish Halakha (see below), it is manifestly obsolete and unrealistic in view of the many nuances and hybrid situations that prevail in present societies. Acknowledging complexity, rather than trying to avoid it, should be the agreed best practice in collecting and analyzing statistical data on the identity characteristics of Jews and of any other sub-population.

These questions bring us back to the important issue of narrative. It will be more accurate to acknowledge that along with the several possible and competing narratives that circulate within the US Jewish community (or Jewish communities), there are several competing narratives among the scholars of Jewish Americans/US Jewry. The difference is that while the grassroots of the Jewish community openly argue about the different alternatives, and in the USA one can barely find one true and significant point of internal consensus (DellaPergola et al. 2019), investigators often act as if they were the custodians of one objective truth. Clearly, rather than one absolute truth, there exist myriad alternative truths conditional upon the very specific sets of assumptions, hypotheses, models, and definitions that the investigator is bound to specify in detail. Short of that transparent rigor, there is no difference between an investigator, a rabbi, a social worker, a lay leader, or just any Jew (or any non-Jew) for that matter.

One important part of the background noise in contemporary Jewish discourse is that Jewish life in the USA and in Israel—the two dominant actors of world Jewry—unfolds under the wings of parallel founding utopias: in the USA, E Pluribus Unum—the Unity of the Many, including the Jews; in Israel, Mizug Galuyoth—the Ingathering of the Exiles, all of them supposedly Jews. E Pluribus Unum and Mizug Galuyoth look very similar, but from a Jewish perspective they are on divergent paths, if not on a collision course. The two different narratives that follow these utopias can affect not only the nature of Jewish experiences, but also the approach to population estimates. Jews in the USA constitute a minority of the total population, successfully integrated in a multi-cultural web, and very attuned to US universal values. Jews in Israel are more religiously conscious, and also more ethnocentric and at times nationalistic. Jewish society is highly heterogeneous in both locales, but one narrative rewards incorporation within Jewry of diversity drawn from US society at large, the other stresses boundary maintenance and draws diversity from within a globally dispersed Jewish people.

To be relevant and respectable, the analyst must make a supreme effort to isolate self from these contrasting conceptual frameworks, to look at the data as they are in a detached fashion as much as possible, and present his or her point of view clearly and without smoke screens. With all due consideration for the quest of “best practices,” as advocated by Tighe et al. (2022), in reality Jewish (and other) population estimates reflect a wide array of theoretical assumptions, technical preferences, and discretionary decisions taken by the principal investigators. All of these must be made explicit and transparent to promote a constructive critical debate in the social sciences and to allow data users to make their own conscious choices. The following is a perspective from demography and population studies.

The Disciplinary Predicament

Demography asks the following basic question: if we estimate a certain Jewish population size at a given point of time in a certain place, what was that same population’s size and profile at an earlier point in time and place, and what were the determinants of change? In formal terms, the fundamental demographic equation reads:

$${\mathbf{P}}\left( {\mathbf{t}} \right) = {\mathbf{P}}\left( {{\mathbf{t}} - 1} \right) \, + \, \left( {{\mathbf{B}} - {\mathbf{D}}} \right) \, + \, \left( {{\mathbf{I}} - {\mathbf{E}}} \right) \, + \, \left( {{\mathbf{A}} - {\mathbf{S}}} \right)$$

where P(t) is the population size at any point in time, called t, and P(t − 1) is the population size at a preceding point in time; B and D stand for the number of births and deaths, respectively, during the same period of time; I and E stand for immigration into and emigration from a given area pertinent to the given sub-population, and when dealing with an ethno-religious sub-population, A and S stand for the numbers of accessions and secessions, i.e., conversions or other modes of identificational change, into and out of the same.

In other words, a population, and as a derivative a community, results from continuous changes reflecting individual and collective histories, as well as local and global societal change. Jews are not like carrots or maize where on a given year the yield was scant, while during a different year one reports a good crop.

In demography, numbers are a function of process; the focus must be on process, not on numbers. The demographer deals with Jews as a population, which is not exactly the same as addressing them as a community. Observation easily shows that a community is a far smaller entity than a population. Many that are ascribed to a population do not feel the need or interest in being part of a community. It should be understood that when we speak of the US Jewish community, we use intuitive rhetorical language. To state that the US Jewish community consists of 7.5 million, or even of 6 million individuals, is quite arbitrary but to address them as a population may be legitimate.

As Tighe et al. (2022) note, in the USA, Jewish population estimates are complicated by a lack of census data or a central population registry on religion. In the effort to analyze the US Jewish population at the national level, three main strategies have emerged (DellaPergola 2022, 350–353):

  1. 1.

    National sample surveys sponsored either by a Jewish organization, like the Jewish Federations did with the 1970, 1990, and 2000-01 NJPSs, or by a non-Jewish organization, like the Census Bureau’s 1957 CPS and the PRC’s 2013 and 2020 surveys of Jewish Americans;

  2. 2.

    Compilations and summations of local Jewish population estimates obtained through a variety of sources, from representative surveys to hearsay (Sheskin and Dashefsky 2022, Hartman and Sheskin 2017);

  3. 3.

    Syntheses of many general social surveys, which comprise small sub-samples of persons self-identifying as Jewish, usually in response to a question on religion (Saxe et al. 2006, 2021; Tighe et al. 2019, 2021, 2022).

Each of these approaches has advantages and disadvantages. While they can all serve as the basis for studying the interrelations between different variables, only the first can be used to infer Jewish population size. The first method also has the advantage of internal consistency, but any methodological shortcoming or technical mistake may have far reaching consequences for the overall results. The second method combines the advantage of local insight with the disadvantage of extremely heterogeneous data due to different definitions of the target population, different data reliability, different instruments, and different timing. When it comes to summing up several local surveys to get a national total, there is a high likelihood of double counts reflecting internal migration or multiple residences. The third method has the advantage of a large database and the disadvantage that it usually covers only religion, potentially leaving out Jews who do not declare a religion (see more below). Along with inconsistency of data quality, the coverage of topics related to Jewish identity is usually very limited. Moreover, whereas the first two approaches may sometimes provide a full profile of the characteristics of all members of a household, the third mostly relies on answers produced by adult respondents only.

Although some readers may think that any users of numbers are demographers because of their reliance on social surveys, in their reporting (and critique) of my work Tighe et al. (2022) do not really enter the domain of demographic analysis. On my side, I made two attempts (both published in this journal, see DellaPergola 2005, 2013) to highlight the components and impact of demographic trends among Jews in the USA since the end of World War II, based on a combined reading of the major national sources. I found very high consistency between the several national studies since the end of World War II to date, dutifully accounting for the intervening changes and all limitations and even errors that occurred (such as manifest under-coverage in the 2000–2001 NJPS). I analyzed known population changes, such as births, deaths, immigration, emigration, joining Judaism, and leaving it. I used forward and backward projections and found that each survey quite closely predicted the outcome of the following one. The emerging picture was one of a moderately growing American Jewish population, at variable paces according to periods of time.

I regret the omission by Tighe et al. (2022) of reference to that effort, as well as their omission of tens of analytic efforts by the best investigators of the demography and the sociology of US Jews. Perusing their list of references, one does not find the rich and highly diverse independent demographic essays of Sidney Goldstein, Paul Ritterband, Uziel Schmelz, Vivian Klaff, Gary Tobin, Egon Mayer with Barry Kosmin and Ariela Keysar, Calvin Goldscheider, Frank Mott, Harriet and Moshe Hartman, Bruce Phillips, Allen Glicksman, Uzi Rebhun, Anne Goujon, Edieal Pinker, and many others.

The 2020 PRC report (Pew Research Center 2021) estimated a total net US Jewish population (NJP) of 7.5 million—an increase of 800,000 over their own 6.7 million estimate in 2013. As a way of comparison, in Israel, the Central Bureau of Statistics estimated 6.7 million Jews in 2020 (not including non-Jewish household members) compared with 5.9 million in 2013—also an increase of 800,000. Israel notoriously has the highest fertility and birth rate of all developed countries in the world, and annually absorbs large amounts of new immigrants (for details see DellaPergola 2020, and 2022, 343–350 and 350–366). But on the face of it, the growth in Jewish populations in the two countries from 2013 to 2020 was identical. Moreover, US Jews allegedly grew faster than the total US population (Chamie 2022). Whether or not we believe that US Jewish population growth is the same as in Israel and faster than the total population growth in the USA, these figures need explanation.

In terms of its chosen definitions and execution method, the PRC 2020 net Jewish Population (NJP) estimate of 7.5 million Jews—the topic of this exchange—represents a creative and discontinuous construct compared with the preceding 60 years of sociodemographic research, including the very same PRC’s 2013 survey of Jewish Americans (Pew Research Center 2013). Part of the change is contingent upon technical reasons, but part reflects changing intellectual and social climates in America. Any new population estimate should be coherent with previous ones in terms of the intervening processes, but eventually those climate changes lead toward changes in the object of investigation through a redefinition of the target constituency, and without due attention to the intervening sociodemographic processes.

As noted, Tighe et al. (2022) seem to believe that in the 30 years since 1990, Jewish Americans could have grown by 2 million, from 5.5 (according to the NJPS—Kosmin et al. 1991) to 7.5 million, at a rate faster than the total US population. That is extremely implausible, considering the substantial total US immigrant influx (legal and illegal) and increased birthrate. In 2020, of the PRC estimate of 7.5 million, 5.3 million were Jews by religion (JBR), including adults and children, and the other 2.2 million were Jews with no religion (JNR). Among the latter, 1.5 million were individuals with no religion and one Jewish parent. In the lack of more explicit evidence, I tentatively assumed that the latter corresponded to the “partly Jewish” people of the 2013 survey. The “partly Jewish” people offer an important insight. In the 2013 PRC survey’s screening procedure, the equivalent of one million “partly Jewish” persons were found and later were included in the full interviewing. However, no mention of the “partly Jewish” people appeared in the 2020 PRC survey (see below). Following the assumption that a Jewish population should include those who see being Jewish as their mutually exclusive identification in the first place, I did not include the “partly Jewish” in my 2020 US Jewish population estimate (designated as the core Jewish population (CJP)—see below for greater detail on population definitions). In other words, operationally and provisionally, I suggested that among the 2.2 million JNRs, only the 700,000 with two Jewish parents should be included in the initial definition, while the other 1.5 million pertain to a broader Jewish population definition (see below). This still implied an upward revision of some 300,000, against the 2013 PRC’s estimate without the “partly Jewish” population included, to allow for a smooth, rather than a brusque, Jewish population progression from 1990 to 2020 (see more details in DellaPergola 2022).

To understand how the Jewish population can or cannot grow in the USA, one should consider that since the end of the Baby Boom in 1964, the fertility of US Jewish women never reached the average of 2.1 children required to maintain a stable population in the long term. This led to comparatively and significantly greater population aging and death rates among US Jews. Nobody in the USA knows (or even takes care to evaluate) how many Jews die every year. The declining percentage of US Jews below the age of 15 and the growing percentage ages 65 and over should be depressing population growth in the best case scenario. Realistically, the US Jewish population would be declining, were it not for new immigrants. In neighboring Canada, where good official statistics do exist, the Jewish population is actually growing, but less than what the total input of net migration would cause (see Brym 2023). But the big immigration waves to the USA of the past are over, and a small number of US Jews continue to make aliya. A myth has developed and got traction about the “750,000 Jews” that allegedly immigrated from the Former Soviet Union (FSU) since the 1990s. Consulting Jewish institutional sources, such as the admittedly selective HIAS (annual) reports, and the same PRC surveys, such a figure is untenable, both in terms of absolute size and the timing of immigration, even considering that many members of those households that immigrated were not Jewish themselves. Another myth concerns the number of Israelis in the USA, sometimes declared to include “one million” people. By any available source, public and private, no such estimates are tenable (see, for example, Cohen 2009). In any case the PRC 2020 data, even allowing for some undercount, do not support those high numbers, ditto the Jewish population increase they should have generated.

The true crux of the US Jewish demographic equation is the identificational balance—formal and informal accessions (becoming Jewish with or without formal conversion) versus secessions (deciding that one no longer identifies as Jewish). The past evidence is that over time hundreds of thousands more people left, rather than joined, Judaism (Pew Research Center 2015; Rebhun 2016). Witness the PRC 2020 finding of 1.9 million Americans who had at least one Jewish parent, or were raised Jewish, but now identify as Christian. The crucial issue then becomes the definition of group boundaries for the Jewish population (who is and who is not to be counted) and those who belong to multiple populations (i.e., people, namely children, who are raised within both Jewish and Christian reference frameworks).

The Methodological Predicament

The data we consume, and upon which we build our narratives and community policies, are affected by the research methods we choose. Researchers making different decisions about who to count will consequently derive different estimates of the US Jewish population. To quote Mike Mohrman, a Washington State demographer (The Economist 2021), “When you change the numbers, you get different results.” In the specific circumstances of the more notable Jewish population surveys, to change the definition of who is a Jew is to change the survey methodology, and to change the numbers.

The 2020 PRC survey’s purpose was explicitly not to compare the profile of Jewish Americans with the 2013 PRC, as the two studies were conducted using different methodologies. In evaluating the latter, however, one cannot ignore the former. In 2013, the survey was conducted by telephone, but sharply declining phone response rates in random-digit dialing (RDD) surveys suggested that the 2020 data collection would be improved using internet-based questionnaires, supplemented by mailed paper questionnaires. Each survey mode has advantages and disadvantages. Different survey modalities (interview, phone, web) may have variable effects on social desirability bias (de Leeuw and Hox 2010). Answering the phone involves a lot of selective bias according to who will answer the call or not, but does not involve effort in initiating the contact or particular skills when answering questions. Clicking in response to a web-based survey and/or carrying an envelope to the nearest postbox involves significantly more selective bias in terms of the respondents’ technical skills and personal initiative. Using address-based survey (ABS) as the mode of national data collection implies risking that a huge number of addresses are out of date, reflective of intensive internal migration and relocation. Moreover, ABS risks significantly over-representing non-Hispanic whites and people with higher levels of education (Link et al. 2008). This looks quite intriguingly suspicious when thinking of the typical characteristics of a Jewish population.

The PRC’s (and several other Jewish social surveys in recent years) reliance on ABS seems particularly problematic in a country like the USA, with its very high degree of geographical mobility. If a research project is aimed at the whole population, such as in the case of commercial polls, it is not crucial to reach a specific sub-population since it is likely that a consumer will substitute another consumer in the apartment left vacant by the former. But when the target is a small minority, like the Jews, the residential substitution between relevant and irrelevant potential respondents is not at all certain. It is regrettable in this respect that the issue of internal migration was ignored along the way, and data about people’s lifetimes and recent movements were not gathered in the PRC questionnaire to provide a sense of the direction of ongoing changes.

The different self-selection biases by response mode were experimentally demonstrated through the 2020 PRC collection of supplementary responses using, in part, the old (phone) and, in part, the new (web plus mail) survey modes. The experimental findings were not included in the main findings, but appeared as an appendix to the main report (Pew Research Center 2021, 239–247). This experiment was an important contribution of the 2020 PRC to elucidating differences between both survey methods and the sociodemography of Jewish Americans. The web-plus-mail 2020 returns brought in younger, less affiliated, more distant fringes of a broadly defined Jewish population. The phone method would have generated more elderly, Orthodox, affiliated Jews, and a less extended population.

Moreover, in 2020, about 90% of the total US population had internet access from anywhere via any device (Statista 2021). We can assume the share among Jews would be closer to 100%, even allowing for limited access among some of the Haredim. Therefore, if we compare the higher internet access among the Jews with the lower internet access of total Americans, the projected percent and number of Jews among total Americans requires downward adjustment, affecting Jewish population estimates accordingly. Moreover, as noted in the 2020 US presidential elections, internet surveys over-represented medium-to-high social classes, among which Jews are concentrated. Joe Biden beat Donald Trump indeed, but the gap between their perceived degrees of popularity was significantly overstated in most surveys. Jews (most of whom identified with Biden) were abundantly part of that upward bias.

The Definitional Predicament

The first confusion to be avoided is between a normative and an operational definitional approach. A normative approach takes on board those who have a Jewish mother or converted to Judaism according to a certified procedure, irrespective of the vagaries of self-definition. Such a procedure would require a retrospective investigation of the ancestry of all those included in a survey, which is virtually impossible in the social sciences because of time and costs. An operational approach, instead, accepts on face value respondents who say “I am Jewish” and counts them as such (provided they do not also have another religion), without ascertaining if they do indeed, e.g., have a Jewish mother or converted to Judaism though a certified procedure.

The successful integration of Jews within the American social fabric brought about the end of the dichotomy in which it was easy to determine who was Jewish and who was not. Such a binary world perhaps existed long ago, but not today. There exist instead endless nuances concerning who self-identifies (and/or is counted) as Jewish and who does not, as well as when and where. Different definitional criteria may make sense in terms of public perceptions in a certain locale, but are not recommended in view of the transnational nature of world Jewry, and the quest to provide data that are comparable across different countries. Americans indeed measure distance in miles, the rest of the world, in kilometers. Americans enjoy US football, the rest of the world primarily play soccer. Wishing to provide a unified global standard on distances or ballgames creates a problem. However, in the global transnational population that Jews constitute, consistent definitional criteria for Jewish population appraisal should apply to all countries in the name of peoplehood, but above all, in terms of clarity and relevance. One cannot define a Jew in one way in one country and in another way in another country. At least one of the many possible legitimate definitions should be kept constant as far as possible to ensure comparability.

Since 1982, I have published annual Jewish population estimates for each country of the world in the American Jewish Year Book. Since 2012, these estimates have been produced according to alternative definitions. One important development was the concept of core Jewish population (CJP) suggested by Kosmin et al. (1991) for the NJPS 1990, as distinct from the net Jewish population (NJP) as defined by the 2013 and 2020 PRC surveys. The CJP includes all who declare themselves to be Jewish by religion, or to have no religion but to be Jewish by ethnicity or parenthood, and to not have another religio-ethnic identity. This definition strives to capture a mutually exclusive Jewish population, with an awareness of the increasing frequency of people identifying as having multiple identities. I also annually offer estimates of the population with Jewish parents (PJP) (regardless of own identification), of the enlarged Jewish population (EJP), which also includes non-Jewish members of the household, and of the Law of Return population (LRP), which addresses the broader pool eligible to immigrate to Israel and receive citizenship and civil rights there.

I never tried to estimate the Jewish population by the Halakha, because this is not feasible operationally. Besides the existence of different Halakic rulings by the Orthodox and the Reform rabbinates, Halakha is a legal approach by which each case should be evaluated on its own merits through an accurate external assessment of personal status across several previous generations. The lack of uniform conversion procedures compounds the issue further. This clearly does not conform with the practice of social scientific sources, which are characterized by immediacy and by relying on information released by the directly interested. Tighe et al. (2022) observe that those born of a Jewish mother are Jewish by Halakha, and therefore should in any case be included in Jewish population estimates, but they omit to add that following the same line of reasoning, self-assessed Jews who do not have a Jewish mother and did not undergo a recognized conversion procedure should not be counted as Jews; instead they are routinely included by me in the CJP.

The goal cannot be a definition by Orthodox Halakha, which would require endless genealogical checks, impossible to perform in a social scientific framework. But categories such as partly Jewish or Jews of multiple religions, which are incorporated as standard in some Jewish population estimates, do not resonate as Jewish to many in the USA and elsewhere. These persons, along with non-Jewish members of Jewish households and others of more distant Jewish ancestry, would be included in broader definitional circles than the Jewish community.

Some analysts provide Jewish population estimates which also include Jews of Other Religions (JOR) (e.g. Aronson et al. 2021). These categories cannot be included in a work, like mine, that has a primary comparative goal transnationally, and must consider and adjust the different persuasions of Jews in different parts of the world. Within the USA itself, the Orthodox, Conservative, and Reform movements would probably not agree on a definition, noting, incidentally, that these organizations are very sensitive to these different approaches and do employ excellent social scientists in their research departments. On the other hand, the more restrictive standards and norms prevailing in Israel can neither be imposed upon other Jewish populations, nor be simply ignored, because they do not conform with those of many Jews in the USA. Israel is part of contemporary world Jewry, and it cannot be left out. The resulting CJP is a compromise: neither conforming to the strict Orthodox Halakha definitions, nor the more expansive constructs preferred by other sections of US Jewry.

The PRC in 2013 and in 2020 did an attempt to synthesize the different approaches and introduced the new concept of net Jewish population (NJP). The NJP was a creative attempt to have one measure for all, but it included categories such as the “partly Jewish” (in 2013) or those without religion who were defined Jewish because of their “family background” and not because of their own choice (in 2020). In 2020, the first PRC question was: “What is your religion, if any?” Respondents answering “Jewish” to this question were automatically included, but they did not mean to state they are religious. They simply indicated that feeling Jewish preserved some meaning for them. In fact, about one half of those who PCR categorized as Jewish by religion actually declared that “religion is not meaningful” in their lives (Pew Research Center 2021). Answering that one has no religion (rather than checking elsewhere, the easy non-committal response of “just Jewish”) points to an initial non-belonging attitude, although many do not deny, and often may also feel proud of, having Jewish origins. Many non-Jews are proud of their Jewish origins as well.

The second PRC question asked was queried only of those who did not indicate that they were Jewish (or some other specific religion) in response to the first question: “Do you consider yourself Jewish in some other way (such as ethnically, culturally, or because of your family background)?” These people were defined by PRC as Jews of no religion (JNR). The vast majority of these had only one Jewish parent. As a result of this question, as noted, the PRC 2020 definition included 2.2 million persons who do not consider their religion to be Jewish. The bigger issue is that the wide and flexible PRC definition of family background covered a broadly enlarged Jewish population beyond the core concept of a mutually exclusive Jewish identification.

The number of Jewish adults by religion was the same in both PRC surveys: 4.2 million—a sign of stability. What increased significantly were adult Jews without religion, and Jewish children—with or without religion. The apparent total 7-year increase of over 800,000, of which nearly 500,000 were children, obviously resulted from different population definitions, besides the already noted survey method effects regarding target populations.

Since the 1990s, a great expansion occurred in the number of persons who in their own words are partly or marginally Jewish. In 2013, PRC estimated a 6.7 million net Jewish population, inclusive of the main category of Jews by religion, as well as Jews without religion, divided between self-identifying Jews and those who were “partially Jewish.” While this was part of the initial screener, the information collected was kept in the database and allowed for comparisons based on the final survey returns. In 2020, Jews without religion were not partitioned into “Jewish” and “partly Jewish” categories; rather, the JNR attribute was extended to all those identifying Jewishly by family background.

One condition that some researchers—this writer among them—require is that Jewish identity be mutually exclusive with respect to other identities. The modality of “partly Jewish,” which appeared in the PRC 2013 survey as a subjective option for those who had initially answered they did not have a religion, contradicted this exclusivity condition. It stemmed from the following question: QA4-TOT “Aside from religion, do you consider yourself Jewish or partially Jewish, or not?” This is why I did not include the self-assessed “partly Jewish” in the core Jewish population estimates derived from the 2013 PRC survey. There were about one million “partly Jewish” individuals in 2013. These partly Jewish individuals responded extremely weakly on various measures of Jewish identity, for the most part even more weakly than many individuals explicitly eschewing Jewish self-definition like the persons of Jewish background (PJB), or persons with Jewish affinity (PJA) (DellaPergola 2015).

In the classifications of the 2020 PRC survey, the concept and response option of “partly Jewish” was not offered, making a direct comparison with the 2013 survey impossible. We should ask now: if there were one million partly Jewish people in 2013—which I could not include in the CJP estimate—where did they go in 2020, when that option was not available to respondents? Did they disappear? Did they shift to “fully Jewish?” For fair disclosure—this was in part due to my uneasiness facing the “partly Jewish” concept, which I now much regret, in my capacity as a member of the 2020 PRC Advisory Committee. An operational solution had to be found to not lose sight of them, respecting the assumption that, if asked, they would probably have confirmed their “partly Jewish” persuasion.

In the meanwhile, two things have happened: the rate of intermarriage—which is the main engine in the creation of these intermediate and nuanced sub-populations—continued to increase steadily (to some extent since 2013 as well); and, as noted, the PRC definition of Jewish without religion was expanded, to include a variety of types, namely “family background.” Family background (two words quite neglected by Tighe et al. 2022 in their text) create a highly ambiguous and porous category, within which many agnostic former Jews, or any descendants of Conversos could find a place. Therefore, the 2020 PRC definition considerably stretched beyond the CJP I use for international comparisons, including those customarily supplied to the American Jewish Year Book (DellaPergola 2022) and to Israel’s Central Bureau of Statistics (see, for example, Israel CBS 2022).

Among the JBRs, a majority actually do not practice the Jewish religion, which they do not find very significant or at all significant in their lives (Pew Research Center 2013, 2021). This means that a very substantial number of secular people are caught within the net of the “by religion” category, and by all means they are ready to define themselves as JBRs for the purpose of answering a survey. But there are also those who are not ready to do so, namely the JNRs, and therefore it is plausible to think that their Jewish identity is different. They cannot be equated to the former, contrary to what Tighe et al. (2022) maintain. Indeed, Tighe et al. (2022) do not deliver the goods when they compare Jewish behaviors of self-defined secular Jews among those who say that they are Jewish by religion. Instead, what needs to be done is to compare the Jewish identity of those who declare they have no religion, are the descendants of one Jewish parent (versus those who have two), and possibly those who say they feel partly Jewish, versus those secular Jews who say Judaism is their religion. As already noted, these two sub-populations are strikingly different (DellaPergola 2015)—the “partly Jewish” being overwhelmingly weaker in their expressions of Jewish identification, even weaker than non-Jews with Jewish background.

The different definitional approaches reviewed here are summarized in Fig. 1, where PRC-based US Jewish population estimates for 2020 are superimposed to a graph originally published with world Jewish population estimates (DellaPergola 2022). There were 5.3 million Jews by religion (4.2 million adults and 1.1 million children together—circle 1) plus another 0.7 million Jews with no religion and two Jewish parents (0.6 million adults and 0.1 million children—circle 2), for a total of 6.0 million of the core Jewish population (CJP) (4.8 million adults and 1.2 million children). Circle 3 represents 1.5 million persons with no religion and one Jewish parent—here considered as a proxy for the “partly Jewish.” These together with the 6 million CJP constitute the 7.5 million PRC’s net Jewish population (NJP) (5.8 million adults and 1.7 million children). According to the PRC, there were another 4.2 million non-Jewish persons with Jewish background (PJB), including 2.8 million adults and 1.4 million children. Of these, 2.3 million people with at least one Jewish parent (represented in circle 4) can be added to the 7.5 million NJP, thus reaching a total of 9.8 million persons with Jewish parents (PJP) (adults and children). Another 1.9 million non-Jewish household members, connected to the CJP (circle 5) or to the PJP (circle 6) are added to reach an estimated enlarged Jewish population (EJP) of 11.7 million (8.6 million adults and 3.1 million children). Finally, another 1.9 million people with some Jewish affinity (PJA) can be taken as a proxy for non-Jewish grandchildren of Jews and their spouses, thus configuring a Law of Return population (LRP) of 13.4 million, of which consisted of 10 million adults and 3.4 million children.

Fig. 1
figure 1

Configuring and defining the US Jewish population, 2020. Circles 1–2, core Jewish population (CJP). Circles 1-3, net Jewish population (NJP). Circles 1–4, population with Jewish parents (PJP). Circles 1–6, enlarged Jewish population (EJP). Circles 1–7, Law of Return Jewish population (LRP). Note areas represented are not proportional to actual population sizes

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The advantage of these definitional constructs is that they are comparable with datasets for other countries in the world, thus allowing for a better evaluation of US Jewish population trends in a comparative context. It can be added that a Jewish population by Halakha (HJP) does exist, but it cannot be empirically ascertained—surely not through the subjective answers provided in a sample survey. This virtual HJP would probably intersect all of the different circles outlined in Fig. 1, also somewhat extending outside the most external circle.

The Predicament of Children’s Identity

Tighe et al. (2022) make frequent reference to the percentage of Jews in the total US population. While probably aware of the inherent limitation of these ratios, they ignore that survey data refer to adult respondents only, while population estimates also incorporate those under 18. Research consistently shows that the share of children has been, and remains, lower among Jews than among the total population, and this for two reasons. One is the lower than average fertility level that has characterized US Jews since the end of the World War II through the peaks and troughs of the Baby Boom and Baby Bust, and again documented in the more recent dearth of births in the USA (Cohen and Chamie 2021).

The second reason is that a certain share of children born to a Jewish parent is not affiliated or identified as Jewish. An effectively Jewish birth rate is quite lower than the US national birth rate. One big issue in Jewish population studies is indeed the treatment of children’s identity. Ideally one should have a full roster of all persons in a household and their characteristics. This good practice was quite rare in recent surveys, and was not fully implemented in the 2020 PRC survey. In the absence of detailed individual information about the identity of children, the diffused practice is to attribute to children the religion of the parent, usually the respondent. Or in our case, all children in a surveyed household are deemed to be Jewish, or “partly Jewish” due to parental self-identification, without really checking the actual identity of those children. This may generate large biases.

When the parent is a person described as a Jew without religion, and possibly self-describing as partly Jewish (in 2013), the automatic attribution of the respective children as Jewish is unwarranted. Table 1 derived from independent processing of the 2020 PRC data shows the amount of Jewish child identity resilience under different combinations of Jewish parenthood. Among JBRs, 74% raised children who were JBR, 5% JNR, and 20% other, including a combination of Jewish and another religion, or straightforwardly not Jewish. Among JNRs the percentages were 3% JBR, 37% JNR, and 60% other. Among the more distant circles of PJBs and PJAs, only 4%–5% of the children were Jewish in any way and 95%–96% were not.

Table 1 Distribution of children of different types of Jewish family background—Pew 2020 Survey.
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Other data clearly demonstrate that the choice to be a JNR is now a function of parent’s intermarriage and no more of ideological secularization, as it could have been in the past. Among those aged 65 and over, 84% of those identifying as JNR had two Jewish parents, while among those aged 18–19, 17% had two Jewish parents. At a certain generational point, some persons may have been classified as Jews of no religion (JNR) while having a non-Jewish parent, a non-Jewish spouse, and a non-Jewish child. These persons are part of the PRC 7.5 million estimate, and, curiously, Tighe et al. (2022) criticize me for not including them in the CJP. Gender matters, and in this case, greater resilience can be expected among those with a Jewish mother rather than among those with a Jewish father. On the other hand, at some point Jewish identity resilience becomes so low that the mistake of non-inclusion into the CJP estimates becomes very small. On the basis of the available evidence, the margin of error in my operational choice is really quite trivial.

The Predicament of the AJPP Estimates

Tighe et al. (2022) extensively mention their own Jewish population estimates based on their independent (and inherently valuable) US Jewish Population Project (AJPP) (Tighe et al. 2021). In this respect, we should note the following intriguing sequence. The AJPP relies on a meticulous synthesis of tens or maybe hundreds of surveys where Jews are classified according to one among several other religions. The total estimate of US adult Jews by religion in 2013 was 4.2 million by the PRC, versus 4.4 million by the AJPP. In 2020, the PRC estimate of Jewish adults by religion remained exactly where it was in 2013: 4.2 million. So far, the estimates look very consistent: nobody will make a big argument about a gap of ± 200,000 (± 4.6%) in two different population estimates reached through independent sources. Thus we appear to have reached consensus on the number of Jewish adults by religion.

There is a difference, however: the PRC surveys had some information on children, whereas most standard social surveys did not. After factoring in the respective children who were defined by their parents as Jewish by religion, or with no religion and no other identity, the PRC estimates of JBR totaled 5.1 million in 2013 and 5.3 million in 2020. It is difficult to extract the AJPP equivalent of that number because they do not have the necessary information.

In 2013, the PRC also gave their own assessment of JNR: 1.6 million adults and children, including 1 million partly Jewish, thus reaching the already mentioned total NJP of 6.7 million. The AJPP cannot have such an estimate of Jews, namely children, without religion because, as noted, they rely on surveys by religion only. To solve the problem, the AJPP take from the 2013 PRC percent of Jews with no religion—an additional population increase of 39%. At this point, the AJPP becomes highly reliant on the PRC, in spite of their claimed independence from it; hence, theirs is no more a self-contained estimate. Elsewhere, Tighe et al. (2009, 2011) persuasively demonstrated that one should not confuse the percentages of Jews reporting no religion in a Jewish-sponsored survey as compared with a general social survey. The PRC, which, as noted, did cover JNRs, is indeed a general organization, but their surveys of Jewish Americans could be easily recognized by respondents as Jewish oriented surveys. Most of the surveys upon which the AJPP relies were not. Therefore, it is manifestly not appropriate to use the estimates of Jews without religion from a Jewish survey to inflate the returns from a set of non-Jewish surveys.

The AJPP not only creates very detailed national, regional, and local Jewish population estimates, which supposedly include those without religion, but also attributes personal characteristics to those Jews without religion. To do that, a complex algorithm is enacted, which through a high number of iterations finds who among those anonymous persons without religion might plausibly be more Jewish based on their other sociodemographic characteristics. They describe this procedure as poststratification weighting with attention to age, race, Hispanic ethnicity, and educational attainment, and along with it they provide a percent Bayesian credible interval that should help evaluate the accuracy of the estimate. Since familiarity with Bayesian methods cannot be assumed, Tighe et al. (2022) might help with some greater elucidation in the name of transparency. In short, the procedure, more simply called imputation, consists of the addition of new cases—each carrying the respective sociodemographic characteristics—into the original file of Jews by religion through some kind of randomization. Interpolating some missing information is, indeed, part of the standard toolbox of statisticians who work with incomplete data. With a few missing cases this may work very well. But with a missing proportion assessed as 35–40% without religion among the total estimated universe, including children about whom nothing is known, this is a huge correction with an enormous risk of bias. To explain the procedure with a grain of humor for the non-technical reader, if in the folk literature we were used to the expression: “my son the doctor” for describing an elderly Jewish woman’s pride about her upwardly mobile son, there is a serious chance here that the procedure here summarized finds a woman who says “my son the doctor,” and thus assumes she must be Jewish and categorizes her and her son (both lacking religious identification) to the Jewish population.

This contradicts a basic tenet in the social scientific study of Jewry that characteristics of Jews and possible differences between Jews and others should be ascertained empirically and not attributed a priori based on hypotheses. Even if the Jews of religion estimates were accurate, the further attempt to extrapolate the real number of Jews from sources that only deal with religion—instead of directly ascertaining the complex nature of Jewish identification—is at best speculative.

And there is more. In 2020, the PRC needed an independent Jewish population estimate to build a sampling framework—stratified by geographic divisions and possibly some other environmental characteristics. The PRC took the AJPP as a yardstick for their sampling framework, which in the meantime had grown to over 7.5 million, including the PRC-based AJPP assessment of those without religion. In the end, the PRC sample, based on the geographical and numerical guidelines provided by the AJPP, found a Jewish population estimate that was extraordinarily close to the AJPP.

Surprising? This is circularity at its best.

Concluding Remarks

In the last analysis, both 7.5 million and 6 million Jews in the USA are tenable estimates, provided the rules of attribution are made clear. The difference between Tighe et al. (2022) and this writer is that the former find it more appropriate to use a broader—and in my view an exceedingly heterogeneous and evanescent—definition of a Jewish constituency. I prefer addressing the possible size, demographic changes, and social structure of a sub-population characterized by conscious and meaningful group links and identity. Tighe et al. (2022), by their choice to adopt a broader definition, seem satisfied with the consequence of lower rates of Jewish participation, along with higher percentages of individuals who cannot identify with any Jewish denomination, and many more who stay away from any of those features that constitute the essence of corporate Jewish life—such as some Jewish family and relational networks, some Jewish knowledge or belief, identifying with some peculiar Jewish value, being a member of some Jewish association, and the like.

Borrowing the example from Canada, where detailed national census data on religion and ethnicity are regularly collected, we may find someone who has no religion and has multiple ancestries so that among his or her eight great-grandparents one was Jewish, two Irish, one Italian, one Ukrainian, one Inoue, one French, and one Canadian. By one mode of observation that person would be counted as Jewish. Stretched to the extreme, this may lead to a sort of one-drop of Jewish blood criterion. By another mode of observation, that person would not be included in the CJP, but surely would be included in a broader definitional reference. For sure that person, by both points of view, is of interest for the sociological observation of Jewry, and it would be a serious analytic mistake to ignore him/her (e.g., DellaPergola and Staetsky 2021). But that person is not really relevant for international comparisons. Both definitional modes have full right to exist, the mistake being to try to mix them (on Canada, see Brym and Hou 2022).

This said, we should acknowledge that there exists a full and uninterrupted continuum in the range between full acceptance of Jewish identity and total refusal of it by persons who potentially might be included. As I argued, it is impossible to draw one unequivocal boundary across that continuum. The broader NJP definition adopted by PRC, and supported by Tighe et al. (2022), includes persons lacking any attachment or interest in being Jewish—especially in the case of children. Jewishness becomes a property that, once acquired, cannot ever be lost. This position, incidentally, may be compatible with a certain interpretation of Halakha. But from a social scientific perspective, and even more for policy purposes, one might better consider the Jews as a socially meaningful collective, rather than a random aggregate of people with an indelibly ascribed trait.

Unlike the normative framework of Jewish law, the concept of a Jewish/non-Jewish binary is over. Infinite intermediate nuances are observable with significant cutting points, which should not be ignored. Where we place those cutting points not only affects the subsequent narratives, but actually directly derives from those narratives. One of my beliefs is that people should be given the right to choose whether they belong or do not belong, are in or out, always and in any case clearly respecting their own different terms of reference.

To conclude these comments, I should note that in a context of rapidly expanding multiple identities, one thing that plagues Jewish social research is the unilateral examination of the Jewish identification component and the ignoring of the other possible components. A balanced research questionnaire, along with exploring the Jewish identificational side of religion, culture, ancestry, beliefs, and behaviors, should give equal attention to the non-Jewish identification side for many of those who may have one. Some past surveys carried a question about attending non-Jewish religious services, but never questions such as: “Do you believe in Jesus Christ?” Or “Do you celebrate St. Patrick’s Day?” Not even the question: “Did you celebrate the last Thanksgiving?” Or even the most taboo question of all: “Do you feel more Jewish or more American?” The last one was part of the toolbox developed by Shimon Herman—another name that has virtually disappeared from the quoted literature—in his path-breaking studies of the structure of Jewish identity (Herman 1977). If we ask Jewish individuals about Jewish topics, we get Jewish, and this creates an optical illusion of Jewish resilience and continuity. If we also ask about non-Jewish topics, in a context where the large majority of younger Jewish households have close personal non-Jewish connections, we will be in a position to better understand what really counts and how deeply and significantly it runs in the minds and propensities of those caught in our samples.

The other missing piece in sociodemographic discourse is a serious contextualization of Jewish trends. Jews do not live in a vacuum. One potent question in the USA is whether this country is becoming more homogeneous or more polarized, more value-neutral or more tribal. Are religious identities enhanced or eroded? The answer is clearly not the same according to subgroups and generations. In the competition between the various US religious and cultural streams, there are those who gain and those who loose. The same is true in the internal competition between different Jewish streams. The data tell us that the religiously orthodox will be more numerous in the future, and they might eventually contribute a growing Jewish population. But in the meanwhile, the continuing evaporation of certain other non-religiously committed sectors counters that growth with losses. To generate an absolute or relative population growth, a given group must be gaining. But it is necessary to make explicit the rationale of why US Jewry should be gaining (or losing) ground vis-a-vis the alternatives that exist. This is not possible without a full reasoning about the nature of US society and the changing role of identities within it, well above its Jewish particularity. This analysis is remarkably absent in the current exchange.

In conclusion, different modes of thought in the social scientific study of Jewry are clearly not only legitimate, but—I believe Tighe et al. will agree with me—necessary and intertwined. Each mode of thought calls for using specific and distinct intellectual and technical tools. I believe in an epistemic community, in which every idea that can be supported by serious reasoning or evidence is acceptable and indeed enriches discourse and makes it more relevant and usable. The value added by proposing different solutions to the same problem is invaluable, each user being, of course, free to choose the version they like the most, or rather find most compatible with their specific needs and interests. In the final analysis, each investigator is free to make her/his choices, provided those choices are clearly explained and justified.

Tighe et al. may be diffident of my CJP concept and estimates, but nobody obliges them to use that particular construct. They can use the Pew’s NJP, which is another legitimate construct, or construct their own model as they skillfully do with AJPP. Moreover, it is absolutely legitimate that organizations like Birthright and Masa include in their target constituency kids whose identity is beyond the core Jewish definition. An organization like Habad in Russia or Ukraine is absolutely entitled to enroll some kids in their Jewish schools that they would not admit in their own schools in Israel.

The important thing when addressing the data, is to always respect history and sociology—both as unfolding collective processes as well as scientific disciplines with years of achievement and a large body of accumulated knowledge. With great consideration for the huge amount of skill and good will invested, a population estimate detached from an assessment of underlying historical and sociological diachronic processes, and severed from relevant spatial comparisons, is not really very useful. It is what the people wish and do, not the principal investigators, that will determine the numbers.