Strengths and weaknesses of citation indices and impact factors

According to Eugene Garfield2, who had the remarkable ability to make a very lucrative business out of recording citations, the idea that citations are the currency through which scientists pay other scientists goes back to the Sociologist of Science Robert K. Merton, who expressed this opinion in a private conversation with Garfield, in 1962. In Garfield’s words, “the Mertonian description of normal science describes citations as the currency of science. Scientists make payments, in the form of citations, to their preceptors”. For many years, however, it was not at all clear how this currency could be converted into dollars and cents (or pounds or euros). The conversion became possible when citation counts became a measure of scientific quality; indeed, a measure actually used to decide on promotion and hiring and to judge grant applications.