Word describing a distinct absence of intellectual curiosity?

Solution 1:

I think "complacent" may be a close answer.

adj. having or showing a lack of interest or concern

Source: Merriam-Webster

(A correct answer would be based on how you describe this person. Does he/she know enough of the subject to not investigate or is the subject of discussion too bland for the person's taste so as to not arouse any interest? If the person is generally disinclined to new things, then perhaps "apathetic" or "numb" would make more sense, however, both these words lean more toward emotion than intellect.)

Solution 2:

I would most likely use the word vapid. M-W gives:

"lacking flavor, zest, interest, animation, or spirit : FLAT, DULL"

I find that in contemporary American use, the word (when a applied to a person) suggests that the person doesn't think too hard about anything.