 A “unigrade” relation \(R\) is a relation that has a definite degree or adicity: \(R\) is either binary or ternary… or \(n\)-ary (for some unique \(n\)). By contrast a relation is “multigrade” if it fails to be unigrade (the expression is owed to Leonard &amp; Goodman 1940: 50). Putative examples include causal, biological, physical, geometrical, intentional and logical relations. Causation appears to be multigrade because a certain number of events may be required to bring about an effect on one occasion, and a different number of events may be required to bring about an effect on another. Similarly, entailment appears to be a multigrade relation because a certain number of premises may be required to entail one conclusion but a different number of premises to entail another. Whether there are any multigrade relations and exactly what it means to be multigrade is a fraught matter (see Armstrong 1978b: 93–4, 1997: 85, 2010: 23–5 and Dixon 2019: 64–7 for arguments against multigrade relations and Morton 1975, Fine 2000: 22, MacBride 2005: 569–93 and Hossack 2007: 45–55 for arguments in favour of them).