摘要：This study discusses the construction of deductive warrant derived from inductive warrant in mathematical argumentations expressed by pre-service teacher. In completing a mathematics task, a problem solver needs argumentation to determine, reveal, and support a reasonable solution. A mathematical argumentation can be analyzed by Toulmin scheme consisting of data, claim, warrant, backing, refutation and qualifier. This study focuses on warrant because it is one quality determinant of an argumentation. Inglis, Mejia-Ramos, and Simpson (2007) mentioned types of warrant in mathematical argumentation, including inductive, structural-intuitive, and deductive. This study aims to describe the construction of deductive warrant in mathematical argumentation. Students must use deductive warrant in mathematical argumentation, and that the truth of the conclusion obtained is absolute and there is no rebuttal. This study uses qualitative approach with written works, think aloud, and interview to collect data. The subjects are asked to investigate the truth of the mathematical statement. The result shows that the subjects, in constructing a deductive warrant, initially used inductive warrant. The subjects use an inductive warrant to reduce the uncertainty of the result, so the needs of using deductive warrant exist to reveal a certain conclusion.
