Crossword puzzle clue "disposition to believe without sufficient evidence"

Disposition to believe without sufficient evidence

Apt to believe without sufficient evidence

"Republicans believe every day is the Fourth of July, but the Democrats believe every day is ___ 15" (Ronald Reagan)

Answer to the riddle "What has rivers without water, forests without trees, and cities without houses?"

Cause of sour disposition

Cordial disposition

"To put an ___ disposition on": Hamlet

Disposition to credulity (and the longest common word that alternates typing hands)