  In any case, his theoretical commitments led him to be suspicious of Grebo's ability to support moral discourse, since he thinks it is unreliable. The situation is especially urgent for the kinds of pre-existing principles that form the (abstract, unchanging) objects of moral conversation. For those are a priori by nature—they exist independently of the experiences about which we might converse.  As such, there is that much greater a burden on moral language for a Lockean like Crummell, since a speaker could not rely on their sensations to support the language they are using. They need to have strong powers of memory as part of their faculty of reason, recalling the timeless a priori principles to be applied to these current facts. (Plato makes a similar point in The Republic, observing the importance of memory in moral reasoning and philosophy, especially in the training of the guardian class.) This helps inform his view that blacks ought to adopt English as a remedy for the linguistic “defects” he thinks plagues Grebo. The ability of English to preserve the complex logical structure of abstract moral reasoning (given its syntactic and semantic structure) recommends it, as well as its infinite productivity.