As we all know, there are two groups of Jews: the affiliated and the unaffiliated. The purpose and role of most Jewish community professionals and volunteers is to move those in the unaffiliated pot into the affiliated one. The winner is the one with the most Jews in the affiliated pot and the fewest Jews in the unaffiliated pot at the end of the game.

Except, of course, that this is nonsense. There is no straightforward dichotomy between the affiliated and the unaffiliated. Dividing the Jewish world into these two groups may be simple and intuitive, but in reality, the groups overlap, and there are shades of affiliation in both.

The binary categories typically emerge from synagogue membership data. Either you are a synagogue member or you are not. According to the latest counts, about 80,000 Jewish households in the UK hold synagogue membership, and about 62,000 do not.

The thing is, within those 80,000 households are Jews who daven three times a day, Jews who turn up at shul once a year, at best, for Kol Nidre, and all manner of Jews in between. And equally, in those 62,000 ‘unaffiliated’ households are Jews who daven three times a day (albeit not many), Jews who are involved in Jewish organisations that aren’t synagogues, Jews who don’t even know what the word ‘daven’ means, and, indeed, a number of non-Jews who happen to live with Jews.

In fact, some analysts argue that the official count for the unaffiliated should exclude those mixed households with both Jews and non-Jews living within them, in order to remove any possibility of non-Jews being captured within the statistics. Technically, this is questionable, as it would also exclude Jews who could potentially be synagogue members, but if we do remove them, we find that there are not 62,000 unaffiliated Jewish households in the UK, but rather about 32,000.

On the other hand, if we adopt a more expansive definition of Jewishness instead, to include, for example, anybody who is eligible for Israeli citizenship under the terms of the Law of Return, we would find that the unaffiliated pot rises to an estimated 100,000 households.

So, even if we insist on maintaining the simple distinction between the affiliated and unaffiliated, it’s difficult to determine the size of the unaffiliated pot. And even when we use official socio-demographic statistics, we can see that the nature of those within it ranges from Jews who are heavily engaged in Jewish life, all the way to those who have never set foot in a synagogue in their lives, and are not, in fact, Jewish at all.

Right now, I am actively working on surveys of Jews in 14 different countries around the world. Each one includes a question — or questions — about affiliation. And each country study conducted so far has picked up vastly different proportions of so-called ‘unaffiliated’ Jews, ranging from less than 10% to well over 50%.

In part, this is due to the different types of communal structures that exist in different places. Some have well-established, centralised systems, where relatively few are unaffiliated to begin with. Others have poorly developed community infrastructures that only attract small proportions of Jews, even though many others continue to regard their Jewishness as an important part of who they are. But partly, it’s also because affiliation means different things in different places. And that suggests that affiliation figures, whilst critical for statistical purposes, are not terribly meaningful in terms of what is actually going on in Jewish people’s minds, hearts and souls.

Yet we continue to use these terms in community discussions and debates all the time. “How can we attract the unaffiliated?” “What proportion of those coming to our programmes are affiliated?” “What kind of balance are we seeking to achieve between the affiliated and the unaffiliated?”

I’m not sure this type of language is very helpful. Not only are the categories somewhat amorphous, they also reinforce a language of “us” and “them.” By implication, we are categorising Jews into those who are like us and those who are not, and classifying the latter group in some way as imperfect, flawed or unfulfilled.

I wonder whether we might devise a less binary, more multi-faceted view of affiliation going forward. Maybe that way, we might make a little more progress engaging those on the periphery of communal life. Whoever they are.

Jonathan Boyd is Executive Director of the Institute for Jewish Policy Research (JPR)