Chemistry is often called the central science because of its role in connecting the physical sciences, which include chemistry, with the life sciences, pharmaceutical sciences and applied sciences such as medicine and engineering. The nature of this relationship is one of the main topics in the philosophy of chemistry and in scientometrics. The phrase was popularized by its use in a textbook by Theodore L. Brown and H. Eugene LeMay, titled Chemistry: The Central Science, which was first published in 1977, with a fifteenth edition published in 2021.
The central role of chemistry can be seen in the systematic and hierarchical classification of the sciences by Auguste Comte. Each discipline provides a more general framework for the area it precedes (mathematics → astronomy → physics → chemistry → biology → social sciences). Balaban and Klein have more recently proposed a diagram showing the partial ordering of sciences in which chemistry may be argued is "the central science" since it provides a significant degree of branching. In forming these connections the lower field cannot be fully reduced to the higher ones. It is recognized that the lower fields possess emergent ideas and concepts that do not exist in the higher fields of science.
