All There Meaning

(idiomatic) Mentally competent; not absentminded.

Example:   Is he all there?
  I don't think he's all there...
  I think he's not all there...
1885, Amelia E. Barr, Jan Vedder's Wife, ch. 1:
  A suspicion that “he was not all there,” and therefore “one of God’s bairns,” had insured him, during his long orphanage, the food, and clothes, and shelter, necessary for life; but no one had given him love.
1922, James Joyce, Ulysses, Episode 15:
  His submission is that he is of Mongolian extraction and irresponsible for his actions. Not all there, in fact.
2011, Julie Keith, The Devil Out There, ISBN 9780307369710, Part 1 (Google preview):
  [S]he smiled at me in a such a silly way, I thought to wonder if she was all there.