Why was there rising antisemitism in late-19th-century Europe, and how did the Jews react to it? Most significant in explaining the rising antisemitism is that there was rising nationalism at the same time and in the same places—well, most significant besides the emancipation of the Jews, which started with the French Revolution. The rising antisemitism was in part a symptom of the rising nationalism. Many Jews of that time reacted to the antisemitism-nationalism with Zionism, which is a kind of Jewish nationalism: not, say, the Jewish-German or Jewish-French kind of nationalism, but the Jewish-Israeli kind of nationalism.

Rising nationalism culminated in the World Wars. At the end of World War One, there were four empires in ruins: the German Empire, the Austro-Hungarian Empire, the Russian Empire, and the Ottoman Empire. From those ruins emerged many nationalities who wanted their own nation states. The Zionists agreed with the zeitgeist of the time: that each nationality should rule itself instead of some nationalities ruling over other nationalities. The antisemitism-nationalism was antisemitic only insofar as the Jews, who were their own nationality, were living among other nationalities. The Zionists agreed: The Jews too should separate themselves. The Jews too should have their own nation state. Most important to understand is that it’s not that the Jews were singled out. For example: Analogous to the anti-Jewish sentiment in, say, Germany and Austria after World War One, there was anti-ethnic-German sentiment at the same time and for the same reason. That is, there was anti-ethnic-German sentiment against the ethnic Germans living outside of the new borders of Germany and Austria. There was hatred against every nationality living outside of its own nation state. Zionism’s answer to the Jewish question was to treat it as one of the many national questions.

Other Jews of that time reacted to the antisemitism-nationalism with Marxism, which argued that it’s not national distinctions that matter but class distinctions. For example—according to Marxism—a German proletarian can relate to a French or Russian proletarian more than they can relate to a German bourgeois. People should identify not with their nationality but with their class.

To go back to the emancipation of the Jews: Emancipation led to a different, non-nationalism-based antisemitism. The ghettoized Jews, segregated from the Christian majority in where they lived and given only a few options for work (e.g., moneylending), were tolerated most of the time. Only here and there did violence break out. But emancipation led to an explosion of Jewish influence on Gentile society, which in turn led to an explosion in the intensity of the Gentile’s long-standing love-hate relationship with the Jews. Pre-emancipation, the love-hate relationship was: “The Jews are useful to the economy, e.g. in doing the moneylending. But we’re jealous of how much money they have.” Post-emancipation, the love-hate relationship came to a head because of the newfound Jewish influence in science, philosophy, music, etc. Emancipation desegregated Jewish influence. It freed the Jews to make much more wide-ranging contributions. But it was only some of the Gentiles who appreciated that. Many Gentiles, especially in Germany, argued that the Jewish “contributions” were in fact not contributions at all. The old antisemitic-anticapitalist argument, which was that the traditional Jewish economic success was fraudulent, was extended. The new antisemitic argument charged the Jews with fraud not only economically but also in science, philosophy, music, etc.

With all of that said: The Jews reacted to the rising antisemitism in late-19th-century Europe, which (as I explained above) was because of nationalism and emancipation, in several ways:

1. Some Jews gave up on Europe and left. Most of those Jews went either (a) to America or (b) to what later became modern Israel.
2. Other Jews didn’t give up on Europe. (a) Some of those other Jews swam with the current of emancipation, despite its at-least-short-term antisemitic effect. They believed in assimilation. For example, the Jewish-German assimilationists believed in thinking, feeling, and acting German. Antisemitism was because of incomplete assimilation. Antisemitism would die with complete assimilation. (b) Other Jews who didn’t “give up” on Europe—well, they did give up on the society of Europe—swam against the current of emancipation. They retreated back to the ghettos. They ghettoized themselves anew. The outside world used to be shut to them, but when it opened up they didn’t like what they saw. They shut it back out themselves.
3. Some of the Jews who swam with the current of emancipation swam against the current of nationalism. Marxism was popular among such Jews.
4. Among the Jews who agreed with nationalism, there were (a) the assimilationists, (b) the non-assimilationists, and (c) the Zionists. For example: (a) The “Jewish-German” assimilationists downplayed or even got rid of the “Jewish” part of their identity. They wanted to be “German” like everybody else—at least that’s what they wanted in public, for in private many of them kept their Jewish identity. (b) The “Jewish-German” non-assimilationists were comfortable with being “Jewish-German.” They wanted to keep both parts of their identity. And (c) the “Jewish-German” Zionists sidestepped the question. They gave up on Germany.
5. In reply to the antisemitic-anticapitalist argument, which had long charged the Jews with economic fraud, some Jews (in the majority) argued for socialism and other Jews (in the minority) argued for capitalism. The socialist Jews in effect replied: “Yes, our people have been greedy. They’ve been exploitative. Antisemitism was for that reason unavoidable. But that’s only because of capitalism. If we get rid of capitalism, then we get rid of the possibility for that greed and exploitation.” And the capitalist Jews in effect replied: “No, our people haven’t done anything wrong. In fact, our people’s economic success has been everybody’s economic success. Capitalism brings everybody more wealth than they’d otherwise have.”

1. Jewish identity is such that you’re either “Jewish by birth” or “Jewish by choice.” The former is traditionally matrilineal: If your mother is Jewish, then you’re Jewish. You’re a born Jew. But some especially liberal sects of modern Judaism make an exception: Even if your mother isn’t Jewish, you’re Jewish as long as (a) your father is Jewish and (b) he raised you Jewish.
2. The traditional or prototypical Jew is a Jew born and raised: His father is Jewish, his mother is Jewish, and he’s raised Jewish and only Jewish. But there are plenty of variations: (a) There are people born Jewish but not raised Jewish. (b) There’s also the opposite: people raised Jewish but not born Jewish. Those are the aforementioned Jewish-father-raised, Jewish-motherless people accepted as Jewish in the especially liberal sects. (c) There are even Jews who were neither born nor raised Jewish. Those are the converts.
3. The converts. Conversion is akin to adoption. You’re “adopted” into the Jewish “extended family.” There are two problems with conversion: (a) It’s rare for people to truly internalize and bring into themselves at the deepest level a culture that they didn’t grow up with. And (b) you can convert to Judaism, yes, but you can’t convert your blood to, say, Ashkenazi blood. The Jews have been incredibly successful in religion, business, philosophy, and science, but thinking that converting to Judaism would give somebody without any Jewish blood the advantages of being Jewish would be akin to thinking that giving up a black baby for adoption to a rich white family would give the black baby the advantages of being white. Of course that would only give one side: the white-cultural advantages. Any white-biological advantages would stay closed to the child. And that analogy is about adoption at birth. Adoption as an adult is even less likely to give any kind of privilege or advantage. Imagine a 30-year-old black man who was raised in a poor black neighborhood being suddenly adopted into a rich white family. He may learn something, sure, and he may teach his adoptive family something as well. But ultimately adults just don’t change very much.
4. The Jews are by and large an extremely stubborn people because the modern-day Jews descend from countless generations of people who refused to convert to Christianity despite persecution. The Jews who converted out took their blood with them.
5. Anybody can say that they’re Jewish in the same way that anybody can say that they’re a native speaker of, say, Japanese. That’s because anybody of any race could conceivably be Jewish and anybody of any race could conceivably be a native speaker of Japanese (or of course of any language). There’s no way to disqualify somebody of either of those qualities by appearance only. There’s nevertheless prejudice or strong association with appearance: Some appearances (e.g., racially Japanese-passing, which is a subset of Northeast Asian) are rare among Jews in the same way that some appearances (e.g., white, black) are rare among native speakers of Japanese. By contrast: It’s not the case that anybody can say that they’re, say, Northeast Asian, white, or black. Race isn’t something that you can convert into or learn. It’s set in stone at birth.
6. It’s possible for anybody of any race to convert to Judaism, which makes it impossible to describe Jewish identity as that of a “racial group.” It’s also possible for any Jew to say that they’re not religious without that making them no longer a Jew, which makes it impossible to describe Jewish identity as that of a “religious group.” What, then, are the Jews? What kind of group are they?
7. The meme that the Jews are the “chosen people” works alongside the matrilineality principle: Christianity is more a religion of choosing, and Judaism is more a religion of being chosen. In Judaism, the matrilineality principle is such that being born to a Jewish mother makes you Jewish whether you agree with that or not. That is, Judaism is such that most Jews don’t choose (to be Jewish)—that’s in contrast to Christianity, which always gives the individual the choice of what to do identity-wise—but are chosen (to be Jewish). Of course there’s also theological foundation to the meme that the Jews are the “chosen people,” but the most parsimonious psychological and sociological explanation is the above: that the matrilineality principle, which is central to Jewish identity, is a principle not of choosing but of being chosen.