If ye were blind (ei tuphloi ēte). Condition of second class with imperfect indicative in the protasis. The old word tuphlos is from tuphō, to raise a smoke, to blind by smoke (literally and metaphorically). Here, of course, it is moral blindness. If the Pharisees were born morally blind, they would, like idiots, be without responsibility.
Ye would not have sin (ouk an eichete hamartian). Regular form for conclusion of second-class condition, an with imperfect.
But now ye say (nun de legete). In contrast to the previous condition. See like contrast in Joh 15:22, Joh 15:24. They arrogantly asserted superior knowledge.
We see (blepomen). The ignorant mob do not (Joh 7:49). It is sin against light and is hopeless (Mar 3:29; Mat 12:31.). “Ye are witnesses against yourselves” (martureite heautois, Mat 23:31).