rhyme or reason, no

no rhyme or reason

A total absence of a reasonable or rational explanation for something. I've looked over it several times, but there's no rhyme or reason to the agreement we were sent this morning.
See also: reason, rhyme

rhyme or reason, no

An absence of common sense or reasonableness, as in This memo has no rhyme or reason. Closely related variants are without rhyme or reason, as in The conclusion of her paper was without rhyme or reason, and neither rhyme nor reason, as in Neither rhyme nor reason will explain that lawyer's objections. This term originated in French about 1475 and began to be used in English about a century later. Sir Thomas More is credited with saying of a mediocre book that a friend had put into verse, "Now it is somewhat, for now it is rhyme; whereas before it was neither rhyme nor reason."
See also: rhyme

no rhyme or reason

or

no rhyme nor reason

If there is no rhyme or reason or no rhyme nor reason for something, there seems to be no logical or obvious explanation for it. There seems no rhyme or reason behind the pricing of many of these products. I can see no rhyme nor reason for the variance in spelling. Note: You can also say that something happens without rhyme or reason. Symptoms appear and disappear apparently without rhyme or reason. Cuts are being made without rhyme or reason. The only motive is to save money to meet Treasury targets.
See also: reason, rhyme