There is no generally accepted definition of “public opinion.” Nevertheless, the term has been employed with increasing frequency since it came into popular usage at the time of the French Revolution, when Louis xvi’s finance minister, Jacques Necker, referred to public opinion as governing the behavior of investors in the Paris money market. Later efforts to define the term precisely have led to such expressions of frustration as: “Public opinion is not the name of a something, but a classification of a number of somethings.” (See Childs 1965, pp. 12-28, for some fifty different definitions.)
In spite of differences in definition, students of public opinion generally agree at least that it is a collection of individual opinions on an issue of public interest, and they usually note that these opinions can exercise influence over individual behavior, group behavior, and government policy. Because public opinion is acknowledged to play a role in several diverse areas, leading writers on the subject have included sociologists (Tonnies 1887; Lazarsfeld et al. 1944; Albig 1956), political theorists (Bryce 1888; Lasswell 1927; Lippmann 1922), social psychologists (Allport 1937; Cantril 1966), and historians (Bauer 1929). Those who are engaged in manipulating public opinion have also made important contributions: for example, politicians (Lenin 1929) and public-relations specialists (Bernays 1923). Differences in definition and approach can be accounted for largely by the differing interests of various categories of students and practitioners.