ABSTRACT
Scientists in the nineteenth century developed an understanding of causal relatedness that was based on emphases made by Hume and Kant. From Hume they appropriated an emphasis on regularity of sequence. Kant shifted attention to states of physical systems and their development over time. It is the states of physical systems that qualify as causes and effects. What emerged from the merger of Hume's emphasis on constant sequential conjunction and Kant's emphasis on the unfolding of states of physical systems is a regularity-between-states view of causality. Developments in nineteenth-century physics and chemistry conformed nicely to the regularity-between-states understanding of causality. The development of classical thermodynamics illustrates physicists' increasing emphasis on relations between states of physical systems. The kinetic theory of gases provides explanations for such macroscopic relations as the laws of Boyle, Charles, and Gay-Lussac. Supporters of the atomic theory maintained that there exist regularities at a microlevel that are associated with the causal sequences at the macrolevel.
