The Reformation, it has been said, changed the course of history. Most people would agree. At the very least, agree or not, they would hold the proposition to be one worth considering. They would be unlikely to reject it out of hand as incapable of being either true or false because it had no meaning. For, of course, “everybody knows” what the Reformation was and, elaborating a little, we can make clear what we meant by changing the course of history. Yet it is just statements of this sort that cause much methodological wrangling. Their controversial nature is due, in large part, to controversy over the status of such terms as “the Reformation” and, generally, group or macroscopic concepts. Since not only history, but sociology, political science, social psychology, and economics also widely use concepts referring to groups and their properties, rather than to individuals, the controversy has wide ramifications. And because there are, as it were, so many vested interests involved, the dispute also tends to acquire an ideological tone not altogether consonant with dispassionate inquiry. Bad temper and mutual recrimination in scientific discussion are generally a sign that ideological defenses are being shored up. Just possibly, a philosopher whose substantive concern in any empirical field is minimal may hope to be considered above the battle, as one who, having no private axe to grind, can be concerned only with clarifying the logical issues involved. In this hope, I wish to explore as systematically as possible the tangled web of issues woven about the status of group concepts and their relationship to those referring to individuals. Intertwined in this controversy are two different issues. One has to do with the nature of the terms or concepts of social science; the other with the nature of its laws and theories and their relationship in turn to those in other areas. The first issue is one of meaning, the second of reduction. Success in unsnarling the various strands of this web may alone help abate the fury of the controversy.