stolidity

[L. stoliditas.]
The state or quality of being stolid; dullness of intellect; obtuseness; stupidity.

Indocile, intractable fools, whose stolidity can baffle all arguments, and be proof against demonstration itself.

noun

Lack of emotion or interest: apathy, disinterest, impassivity, incuriosity, incuriousness, indifference, insensibility, insensibleness, lassitude, lethargy, listlessness, phlegm, stolidness, unconcern, uninterest, unresponsiveness. See feelings.

The noun has 2 meanings:

Meaning #1: apathy demonstrated by an absence of emotional reactions
  Synonyms: emotionlessness, impassivity, impassiveness, phlegm, indifference, unemotionality

Meaning #2: an indifference to pleasure or pain
  Synonyms: stoicism, stolidness