a road, alley, etc., that is open at only one end.
2.
a position or situation offering no hope of progress or improvement:
That line of reasoning will only lead you up another blind alley.
Origin
1575-85
Examples from the web for blind alley
Whether scientists have faith or not is a bit of a blind alley.
Too often that mistake has led us up the blind alley of advocacy.
Three decades of wishful thinking and building space ambitions on an inadequate funding basis has led us into a blind alley.
British Dictionary definitions for blind alley
blind alley
noun
1.
an alley open at one end only; cul-de-sac
2.
(informal) a situation in which no further progress can be made
Idioms and Phrases with blind alley
blind alley
A dead end; a position without hope of progress or success. For example, That line of questioning led the attorney up yet another blind alley. This term alludes to a street or alley that has no outlet at one end. [ Mid-1800s ]