How does Aristotle’s term logic differ from propositional logic?

Aristotle’s logic is fundamentally a term logic, whereas propositional logic treats entire propositions as its basic units.123

Aristotle’s Term Logic

Aristotle’s system, known as syllogistic, focuses on the internal structure of simple declarative statements. It analyzes how terms (subjects and predicates) relate to one another within a proposition. For example, in the syllogism "Every Greek is human; every human is mortal; therefore, every Greek is mortal," the logic relies on the relationships between the terms "Greek," "human," and "mortal". Aristotle used variables (such as $\alpha$, $\beta$, and $\gamma$) as placeholders for these terms to identify valid patterns of inference.421

Propositional Logic

In contrast, propositional logic (or sentential calculus) treats propositions as unanalyzed wholes. Instead of breaking a statement down into its constituent terms, it focuses on how entire propositions are combined using logical connectives such as "and," "or," and "if...then". While Aristotle’s work primarily analyzed categorical propositions, the Stoic logicians later developed a system that focused on these hypothetical or compound propositions, using variables to represent entire statements rather than individual terms.2354