 Whether this represents a faithful account of Popper’s falsificationism, or whether falsificationism represents the optimal (or even a desirable) mode of scientific reasoning has been a matter taken up by philosophers (Hull 1983, 1999; Sober 1988b), though that is, in some ways, beside the point. (For a philosophically-minded biologist’s survey of the role of Popper in systematics, see Gaffney 1979, Rieppel 2008, or Santis 2020.) Regardless, characterizing parsimony in falsificationist terms provided an important justification that resonates to this day. More recent invocations of Popper in phylogenetic inference have focused on whether parsimony or model-based methods such as Maximum Likelihood  (§1.2.3)  better align with falsificationism (e.g., Siddall &amp; Kluge 1997; de Queiroz &amp; Poe 2001, 2003; Kluge 2001), and whether probabilistic and statistical reasoning is relevant for studying singular historical events (Siddall &amp; Kluge 1997; Haber 2005). (See Turner 2007; Cleland 2011;Currie 2018, 2019, for general philosophy of historical science.) In  section 2.4  we describe how Felsenstein’s (1978) discovery that parsimony is prone to systematic errors poses a serious challenge to this underlying falsificationist justification.