there's no rhyme or reason to/for something

no rhyme or reason

No particular logic, sense, method, or meaning to a given situation, action, person, thing, group, etc. I've looked over it several times, but there's no rhyme or reason to the document we were sent this morning.
See also: no, reason, rhyme
Farlex Dictionary of Idioms.

there’s no ˌrhyme or ˈreason to/for something

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without ˌrhyme or ˈreason

no sense or logical explanation: There has been no rhyme or reason to market movements in recent weeks. Changes were being made without rhyme or reason.This phrase comes from Shakespeare’s play As You Like It: ‘But are you so much in love as your rhymes speak?’ ‘Neither rhyme nor reason can express how much’.
See also: no, reason, rhyme, something
Farlex Partner Idioms Dictionary
See also:
  • neither rhyme nor reason
  • no rhyme or reason
  • rhyme
  • rhyme or reason, no
  • rhyme or reason
  • a bad apple spoils the (whole) barrel
  • a rotten apple spoils the (whole) bushel
  • one rotten apple spoils the (whole) barrel
  • one rotten apple spoils the (whole) bunch
  • rotten apple spoils the barrel