Ibn Ezra on Genesis 18:21:2:

AND IF NOT, I WILL KNOW. Eda’ah means I will have pity upon them. They similarly interpret va-yeda Elohim (and God took cognizance of them)⁴²That va-yeda Elohim means God pitied them. (Ex. 2:25). However, I believe that this verse is to be explained as follows: I will go down and see if all of them (kalah) have done this evil.⁴³According to I.E. kalah (altogether) is to be rendered as all, as in Ex. 11:1 (Krinsky). Have done this evil is a paraphrase of according to the cry of it, which is come unto me. For in truth,⁴⁴The reason that Scripture relates that God went down to see if they all did according to the cry that came before him. God who is All knows the individual in a general rather than in a detailed manner.⁴⁵Ibn Ezra seems to be saying that “Ordinarily…God does not know the particular individual as such. He knows him only as implied in the whole” (Husik, p. 193). Thus it was necessary for God to go down and see. Nachmanides criticized Ibn Ezra on this point for introducing alien philosophical concepts into Judaism. Cf. Nachmanides’ commentary on the Pentateuch, on this verse. Other commentaries could not accept the literal implication of Ibn Ezra’s words and harmonized his comments to conform to traditional thinking. See Krinsky. Some argue that this comment did not come from I.E.’s hand but was inserted in the text by a misguided student. Proof that this interpretation is correct, although it is a great mystery, is Abraham’s plea, Wilt thou indeed sweep away the righteous with the wicked (v. 23).⁴⁶Abraham asked God not to judge Sodom by his general knowledge but to look upon each of the city’s inhabitants as an individual. The heh of ha’af (wilt) is vocalized with a pattach ⁴⁷An interrogative heh is vocalized with a chataf pattach. even though it is an interrogative heh, because it is followed by an alef, which is a guttural, and it is the rule in Hebrew to elongate the vowel before gutturals.⁴⁸