In yogic philosophy, the everyday world is actually an illusion (known as maya). The yogin (practitioner of yoga) overcame maya through his yoga practices.
Such efforts to overcome the effects of karma and consequent rebirth in samsara demonstrate that one’s actually karmic state at any given time was ambiguous or unknown.
Because the direct cause-to-effect process of causation of karma is a bit ambiguous, astrology has been used to try to discern when one should do things (travel, harvest a field, get married, etc.) so as to avoid inadvertently committing an inauspicious act leading to bad karma.