 So far we have considered intertheoretic relationships between chemistry and physics. What about within chemistry itself? Do the macroscopic and microscopic theories of chemistry align perfectly? Are all macroscopic properties of substances ultimately reducible to microscopic properties? In other words, if we have a macroscopic description of matter and a thermodynamic theory about how it behaves, can all of this be reduced to a molecular description? The answer has seemed to be “yes” to many philosophers and chemists, but philosophers of chemistry have urged caution here.