Reichenbach disagreed with the logical atomists and logical positivists, who felt that objects of scientific study could be described as if they were made up of sense data. His own realist view became known as physicalism. He argued on pragmatic grounds for a probabilistic interpretation of induction, so that induction could be expressed in terms of probabilities of future events based on the occurrence of these events in the past.

Reichenbach also developed a triple-valued logic in which statements could be true, false, or indeterminate, for quantum theory. He added the option of “indeterminate” to “true” and “false.” Quantum theory specifies that some events could not be determined even though their causes were known, so it was important to add indeterminacy to a system of formal logical notation. Although much of his work is highly technical, his The Rise of Scientific Philosophy (1951) is a clear and somewhat generalist account of his perspective.