In the field of linguistics, broken plurals is a grammatical phenomenon typical in many Semitic languages of the Middle East and Ethiopia in which a singular noun is "broken" to form a plural rather than by merely adding a prefix or suffix to the original singular noun, as in English. (Example: cat -> cats) Broadly conceived, linguistics is the scientific study of human language, and a linguist is someone who engages in this study. ... Semitic is an adjective referring to the peoples who have traditionally spoken Semitic languages or to things pertaining to them. ... A map showing countries commonly considered to be part of the Middle East The Middle East is a region comprising the lands around the southern and eastern parts of the Mediterranean Sea, a territory that extends from the eastern Mediterranean Sea to the Persian Gulf. ... Prefix has meanings in linguistics, mathematics and computer science, and telecommunications. ... Suffix has meanings in linguistics and nomenclature. ...
Bratman avoids positing a plural agent by trying to explain collective intentions in terms of individual attitudes with common contents that are distinctively social in the sense that solitary individuals could not have them.
Plural subjects are formed when each of a set of individual agents expresses willingness to constitute, with the others, the plural subject of a goal, belief, principle of action, or other such thing, in conditions of common knowledge.
So her analysis of plural subjecthood does not contain the technical notion of a plural subject and her analysis is not circular.