Charles Ellicott Commentary Psalms 82:5

"They know not, neither do they understand; They walk to and fro in darkness: All the foundations of the earth are shaken." — Psalms 82:5 (ASV)

Here we imagine a pause—that interval between warning and judgment which is God’s pity and humanity’s opportunity; but the plea falls dead, without a response. The men are infatuated by their position and blinded by their pride, and the poet, the spectator of this drama of judgment, makes this common reflection. The perversion of judgment strikes him, as it could not fail to do, as an indication of total anarchy and a dissolution of society, a convulsion like an earthquake.

They know not: Compare to Psalm 58:4, They have no knowledge; there, too, it speaks of judges corrupted by the moral blindness which, as in the case of Lord Bacon, sometimes so strangely darkens those in whom intellectual light is most keen.

They walk on in darkness: Or, better, They let themselves walk in darkness; the conjugation implying that inclination or will, and not circumstance, brings about this dullness regarding the dictates of justice and right.

All the foundations...: The very existence of society is threatened when the source of justice is corrupt.

“Back flow the sacred rivers to their source,
And right and all things veer around their course;
Crafty are men in council, and no more
God-plighted faith abides as once of yore.”

Euripides, Medea, 409.