  Pluralists can make concessive or non-concessive responses to the instability challenge. A concessive response grants that such a truth property exists, but maintains that it poses no serious threat to pluralism. A non-concessive response is one intended to rebut the challenge, e.g., by rejecting the existence of a common or universal truth property. One way of trying to motivate this rejection of \(F_U\) is by attending to the distinction between sparse and abundant properties, and then demonstrating that alethic properties like truth must be sparse and additionally argue that the would-be trouble-maker \(F_U\) is an abundant property. According to sparse property theorists, individuals must be unified by some qualitative similarity in order to share a property. For example, all even numbers are qualitatively similar in that they share the property of being divisible by two without remainder. Now, consider a subset of very diverse properties \(G_1 , \ldots ,G_n\) possessed by an individual \(a\). Is there some further, single property of being \(G_1\), or …, or \(G_n\) that \(a\) has? Such a further property, were it to exist, would be highly disjunctive; and it may seem unclear what, if anything, individuals that were \(G_1\), or …, or \(G_n\) would have in common—other than being \(G_1\), or …, or \(G_n\). According to sparse property theorists, the lack of qualitative similarity means that this putative disjunctive property is not a property properly so-called. Abundant property theorists, on the other hand, deny that qualitative similarity is needed in order for a range of individuals to share a property. Properties can be as disjunctive as you like. Indeed, for any set \(A\) there is at least one property had by all members of \(A\)—namely, being a member of \(A\). And since there is a set of all things that have some disjunctive property, there is a property—abundantly construed—had by exactly those things. It thus seems difficult to deny the existence of \(F_U\) if the abundant conception of properties is adopted. So pluralists who want to give a non-concessive response to the metaphysical instability challenge may want to endorse the sparse conception (Pedersen 2006). This is because the lack of uniformity in the nature of truth across domains is underwritten by a lack of qualitative similarity between the different truth properties that apply to specific domains of discourse. The truth property \(F_U\) does not exist, because truth properties are to be thought of in accordance with the sparse conception.