In Jainism, karma is not seen as a merely “external influence” in the Buddhist sense.

Jain view: Karma is a subtle form of matter (pudgala) that actually enters and binds to the soul (jiva) because of passions like anger, pride, deceit, and greed, along with actions of body, speech, and mind. So it is external in origin, but once it binds, it becomes part of the soul’s karmic covering and affects the soul’s inner conditions such as knowledge, perception, energy, and happiness.

How external karma affects internal processes in Jainism

• Asrava: karmic particles flow toward the soul.
• Bandha: they bind to the soul.
• Udaya: they mature and give results.
• Nirjara: they are shed through austerity and right conduct.

So the “external” karma influences internal processes because it contacts, binds, and obscures the soul’s own qualities. It is not just a mental impression or symbolic force; it is a real karmic material association with the jiva.

Important Jain distinction

Jainism does not say karma becomes “internal again” as a psychological state. Rather, karma is subtle matter bound to the soul, and the soul remains inherently pure, while karma only covers or disturbs its original nature.

In short

• External source: karmic matter flows in.
• Internal effect: it binds to the soul and obscures its qualities.
• Goal: stop influx, avoid bondage, and remove bound karma through right faith, right knowledge, right conduct, and austerity.

If you want, I can also explain this in the language of asrava, bandha, samvara, and nirjara in a very simple chart.