Sanskrit
यत्तु कृत्स्नवदेकस्मिन् कार्ये सक्तमहैतुकम् । अतत्त्वार्थवदल्पं च तत्तामसमुदाहृतम् ॥ २२ ॥
yat tu kṛtsnavad ekasmin kārye saktam ahaitukam atattvārthavad alpaṃ ca tat tāmasam udāhṛtam
Translation
While that which clingeth to each one thing as if it were the whole, without reason, without grasping the reality, narrow, that is declared to be dark.
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
Tamasic knowledge clings to one small, particular thing as if it were the whole — irrational, ungrounded in the real, and narrow. The failure mode here isn’t ignorance in the sense of knowing nothing, it’s a kind of myopic overinvestment: mistaking a fragment for the totality, the inverse of verse 20’s ability to see the totality within every fragment.