Suppes was born on March 17, 1922, in Tulsa, Oklahoma. He grew up as an only child, later with a half brother George who was born in 1943 after Patrick had entered the army. His grandfather, C.E. Suppes, had moved to Oklahoma from Ohio. Suppes' father and grandfather were independent oil men. His mother died when he was a young boy. He was raised by his stepmother, who married his father before he was six years old. His parents did not have much formal education.
Suppes began college at the University of Oklahoma in 1939, but transferred to the University of Chicago in his second year, citing boredom with intellectual life in Oklahoma as his primary motivation. In his third year, at the insistence of his family, Suppes attended the University of Tulsa, majoring in physics, before entering the Army Reserves in 1942. In 1943 he returned to the University of Chicago and graduated with a B.S. in meteorology, and was stationed shortly thereafter at the Solomon Islands to serve during World War II.
Suppes was discharged from the Army Air Force in 1946. In January 1947 he entered Columbia University as a graduate student in philosophy as a student of Ernest Nageland received a PhD in 1950. In 1952 he went to Stanford University, and from 1959 to 1992 he was the director of the Institute for Mathematical Studies in the Social Sciences (IMSSS). (He was later to become the Lucie Stern Professor of Philosophy, Emeritus, at Stanford.
In the 1960s Suppes and Richard C. Atkinson (the future president of the University of California) conducted experiments in using computers to teach math and reading to schoolchildren in the Palo Alto area. Stanford's Education Program for Gifted Youth and Computer Curriculum Corporation (CCC, now named Pearson Education Technologies) are indirect descendants of those early experiments. At Stanford, Suppes was instrumental in encouraging the development of high-technology companies that were springing up in the field of educational software up into the 1990s, (such as Bien Logic).
One computer used in Suppes and Atkinson's Computer-assisted Instruction (CAI) experiments was the specialized IBM 1500 Instructional System. Seeded by a research grant in 1964 from the U.S. Department of Education to the Institute for Mathematical Studies in the Social Sciences at Stanford University, the IBM 1500 CAI system was initially prototyped at the Brentwood Elementary School (Ravenswood City School District) in East Palo Alto, California by Suppes. The students first used the system in 1966.
During the 1950s and 1960s Suppes collaborated with Donald Davidson on decision theory, at Stanford. Their initial work followed lines of thinking which had been anticipated in 1926 by Frank P. Ramsey, and involved experimental testing of their theories, culminating in the 1957 monograph Decision Making: An Experimental Approach. Such commentators as Kirk Ludwig trace the origins of Davidson's theory of radical interpretation to his formative work with Suppes.