Paul E. Newton's "Clarifying the Consensus Definition of Validity" addresses the single most important, yet stubbornly protean, value in educational and psychological assessment. "Standards for Educational and Psychological Testing" (American Educational Research Association, American Psychological Association, & National Council on Measurement in Education, 1999) defines validity as the degree to which evidence and theory support the interpretations of test scores entailed by proposed uses of tests. Newton proposes an elaboration to increase precision, consistency, and clarity for guiding testing practice: "An assessment-based decision-making procedure is valid if the argument for interpreting assessment outcomes (under stated conditions and in terms of stated conclusions) as measures of the attribute entailed by the decision is sufficiently strong." Informal argument is mentioned only in passing, but I argue that the tools and concepts of evidentiary reasoning, a variety of informal argument, add insight into the issues Newton wrestles with. I also disagree with defining validity as the binary judgment of whether the argument is strong enough to justify the proposed interpretation. (Contains 1 footnote.)