Subjectum

Subjectum is a Latin noun used in philosophy, logic, and the history of thought to denote the subject of a proposition or inquiry. The term derives from the Latin neuter noun subjectum, related to subjectus, historically used to mean “that which is subjected” or “the bearer of predication.” In scholastic and medieval philosophy, subjectum refers to the term that bears the predicate in a categorical proposition; for example, in “All humans are mortal,” “humans” is the subject, while “mortal” is the predicatum. The subject is contrasted with the predicatum (the predicate) and with the term representing the copula linking them. In logic, the subject term is the grammatical and logical bearer of a property.

In broader philosophy and epistemology, subjectum often denotes the subject in the sense of the thinker or knower—the conscious agent who has experiences or knowledge. This usage aligns with the modern distinction between subject and object, where objectum or res are the things known or acted upon. The Latin term thus covers both the grammatical role in propositions and the metaphysical role of the agent or knower in discourse.

Today, subjectum survives primarily in historical or scholarly discussions of Latin translations of Aristotelian and Scholastic logic. In ordinary English-language philosophy and grammar, the word “subject” is used instead, with subject, predicate, and object as standard terms. The Latin form appears mainly in critical editions, glossaries, and introductions to medieval logic.