 While there are still important disagreements regarding phylogenies, the nature of these disputes have changed substantially as phylogeneticists no longer rely largely on individual expert judgment. The mid-twentieth century saw the introduction of competing accounts of the theoretical foundations of systematics  (§1.2.1),  a flurry of new algorithmic methods for constructing phylogenies and taxonomic classifications, and the beginning of relatively easy access to and employment of computational power  (§1.2.3),  all combined with new sources of evidence in the form of various kinds of molecular data  (§1.2.2).  As biologists sought to incorporate these emerging features into phylogenetic method and theory, debates arose over how (or whether) this fundamentally changed the nature of systematics. At the same time, debates about the foundations of systematics and the proper methods for classification and taxonomy became highly prevalent and interwoven with arguments about these new methods and newly available data.