Walter Carnielli is an Italian-Brazilian mathematician, logician, and philosopher. He is currently a full professor of logic at the State University of Campinas (UNICAMP). He obtained his Bachelor and MsC degrees in mathematics at the State University of Campinas, where he also earned his PhD under the supervision of Newton da Costa. Subsequently, he served as a research fellow at the University of California in Berkeley, following an invitation by Leon Henkin.

His areas of interest are many-valued logic and paraconsistent logic, combinatorics, modulated logics, and combinations of logics. Carnielli has contributed to the proof theory and semantics of many-valued logics and paraconsistent logics; his tableau method for many-valued logics generalized all previous treatments of the subject. He is also the founder of possible-translations semantics, a new semantical interpretation for paraconsistent logics and several other logics that contributed to a revival in the philosophical interpretation of paraconsistency. Carnielli also proposed, with collaborators, the logics of formal inconsistency, a deep generalization of paraconsistent logics that systematize a large class of paraconsistent logics.

He has also published on finite and infinite combinatorics, and developed (with collaborators) modulated logics, a new kind of logics that allow the formalization of qualitative reasoning by means of special generalized quantifiers. His research also includes model theory, non-classical logics, and foundations of quantum computation and combinations of logics.

Carnielli served as a Director for the Centre for Logic, Epistemology and the History of Science at UNICAMP for three terms, and served as President of the Brazilian Logic Society. He was distinguished with an Alexander von Humboldt Grant for long-term research stays in Germany, and served as en editor and/or a member of editorial boards of major journals, including Studia Logica, Logic and Logical Philosophy, Journal of Applied Logic, CLE e-Prints, Reports on Mathematical Logic, and Journal of Applied Non-Classical Logics. He is currently executive editor of the Logic Journal of the IGPL.

Carnielli is a recipient of the Telesio-Galilei Gold Medal Award 2012 in Philosophy and Mathematics and winner of the Jabuti Prize, the most prestigious literary prize in Brazil.

Almost 90 of his papers in logic, philosophy, foundations of mathematics, combinatorics, computability, and set theory have been published, in addition to almost 12 books.