"Now obviously the propositions of the system have reference to matters of empirical fact; if they did not, they could have no claim to be called scientific"

This quote by Talcott Parsons is referring to the idea of a scientific system. A scientific system is a set of propositions that are based on empirical facts, meaning facts that can be observed and tested. Parsons is saying that if a system of propositions does not have any reference to empirical facts, then it cannot be considered scientific. This is because scientific systems are based on facts that can be proven and tested, rather than just theories or ideas. Therefore, if a system of propositions does not have any reference to empirical facts, then it cannot be considered scientific. This quote by Parsons emphasizes the importance of empirical facts in scientific systems, and how they are essential for a system to be considered scientific.