A method and system for inferring facts in parallel in a multiprocessor computing environment is provided. An inference system infers facts by applying rules to a collection of existing facts. For each existing fact, the inference system schedules a thread to apply the rules to that existing fact. As a thread infers a new fact (i.e., one that is not already in the collection of facts), the thread adds that inferred fact to the collection of facts. When a thread adds a new fact to the collection, the thread also applies the rules to that new fact. After the threads complete execution, the inference system may apply the rules to the facts of the collection, including the newly inferred facts, by again launching a thread for each fact to apply the rules to that fact. The inference system performs this processing iteratively until a termination condition is satisfied.