The going (non-anti-Semitic) theory as I understand it is that the anti-semitic laws of the middle ages prevented Jews from earning money through traditional aristocratic means (i.e. Land ownership), instead some Jewish families gained wealth through more intellectual means such as banking, law and medicine, this fostered a culture where knowledge was valued. During the rapid growth of the middle classes in the 18th and 19th century, those Jewish families that traded in these occupations began to establish comfortable levels of upper-middle class wealth. The sons of these upper middle class Jewish families, freed from the urgent need to earn a living and nurtured in a more intellectual atmosphere, studied the arts, music, science and the like. Unburdened from aristocratic conservatism, bought up in an intellectual culture and with sufficient wealth to pursue unprofitable occupations, they were in the ideal position to come up with novel and radical ideas, hence their cultural importance, and relative prominence given the small proportion of the population that was Jewish.

It's also worth noting that the requirement to learn and recite the Torah, meant there had always been far higher rates of literacy in the Jewish population than in the general population.

The current theory in vogue is based on a paper published by Cochran and Harpending in the mid-2000s. It relies on an analysis of population genetics and argues that between about 700 and 1600 European laws forced Jews into non-farming roles requiring high intellectual ability. This plus the very strong in-group breeding among Ashkenazi Jews meant that intelligence was a trait strongly selected for over the generations, leading to a dramatic increase in mean IQ over a period of, say 20 generations. I urge you to google the paper and take a gander. It's very fascinating stuff and underpinned by a lot of sophisticated/technical analysis of the prevalence of certain diseases and disorders among Ashkenazi Jews that are consistent with the particular "intelligence" genes that were selected for throughout European history.

Mod note: I've removed the comments so far, which are simply debating amongst themselves why OP might assume that Jewish people are in fact disproportionately represented.

Answers attempting to actually address the question (including whether or not that assumption is true) are welcome.