Blurriness -- in the sense of blurred realities --- is in opposition to the clear, distinct pictures of reality that emphasis clarity.
For instance, Wittgenstein in the Tractatus Logico-Philosophicus appeals to clarity when he characterises the aim, task and results of philosophy. The task for philosophy is to make thoughts clear; whilst making a thought clear is making clear a picture of reality.
Analogue photography's representations were traditionally seen capturing a slice of real life in terms of the conventions of clarity and sharpness. Photographic realism was interpreted as faithfully representing the reality of the material world--a framed, cut-out of reality. Representing was understood in terms of clarity with clarity interpreted as depicting (abbilden in Wittgenstein) which was then interpreted as mirroring or copying. Photographic theory from Bazin, Benjamin, Barthes, Berger, Sjarkowski, up until the mid-1970s was in general preoccupied with the documentary and the vernacular.
In contrast, Claude Monet's Water Lilies have a blurry, out-of-focus effect that characterises the wide stretches of water. This aspect of Monet’s later work was an actual aesthetic choice, and rather than being a loss of distinctiveness, the indistinct can be interpreted in terms of the aesthetic category of blurriness. Blurriness as an out of focus aesthetic is associated with the transitory, contingency, disorder, movement, incompleteness, ambiguity, the indeterminate, the indistinct, the poetic, the formless.