The study of how individual preferences, judgements or votes can be combined into a collective decision, using formal conditions to compare voting rules and welfare criteria.
In more detail
Pioneered by Condorcet and Borda in the 18th century, the field took off with Arrow's 1951 book. Core results include Arrow's impossibility theorem and the Gibbard–Satterthwaite theorem on the manipulability of voting rules. Social choice supplies the formal vocabulary for debates on voting methods, majority cycles and the limits of aggregating preferences.