 A further distinction adds to the multiplicity of notions of bruteness. This is the distinction between explanations and relations that “back” explanations. The relation of causation, it is often claimed, backs causal explanation: what makes it true that a given fact causally explains another fact is that the former causes the latter or that some event causes another event. Likewise, some philosophers distinguish between the relation of grounding and grounding explanations (see §4 of the entry on  metaphysical grounding).  Corresponding to these various relations are various notions of being brute, which must be distinguished from the notions introduced above: being brute qua uncaused, being brute qua ungrounded, etc. These notions deserve to be put under the label “metaphysical bruteness”, just like the notions defined in terms of explanation that we did put under this label above.