Johan de Kleer is a Dutch-Canadian computer scientist working in the fields of cognitive science, electrical engineering, and computer science.^[2] He is a Research Fellow at Xerox PARC, where he leads the Model Based Reasoning (MBR) group.^[2]

He studied mathematics and computer science at the University of British Columbia, earning a bachelor's degree, and completed a master's degree and a PhD in 1979 in computer science at the Massachusetts Institute of Technology under Gerald Jay Sussman with the dissertation "Causal and teleological reasoning in circuit recognition".^[1] Research areas initiated by him include Qualitative Reasoning, Assumption-based Truth Maintenance System (ATMS), and Model-Based Diagnosis.

In 1987, he received the IJCAI Computers and Thought Award. He is a Fellow of the Association for Computing Machinery (ACM) and the AAAI.

De Kleer is known for his work on qualitative reasoning, model-based diagnosis, design, and truth maintenance systems.^[6,3] In his works, he has maintained that self-aware systems will be using formal language and will be distinguished for an emphasis on math.^[4] De Kleer is noted for his works on qualitative analysis of electrical systems. An example is his conceptualization of the Incremental Qualitative Analysis, a causal qualitative analysis technique that became the basis of a program called QUAL, which is used to describe and recognize the functionality of bipolar circuits.^[5] De Kleer won the Computers and Thought Award from IJCAI in 1987 for his work in qualitative reasoning. According to English Wikipedia, he is a fellow of the Association for the Advancement of Artificial Intelligence (AAAI) and the Association for Computing Machinery, whereas Albanian Wikipedia identifies him as a member of both organizations.^[7,8]

De Kleer has three daughters.^[9] His middle daughter, Katherine de Kleer, is a professor of planetary science at Caltech.^[10]