Consider a thought experiment :-
I have an enemy. He wants to shoot me.
Case A: If I receive the bullet on my body, then the most general explanation given by Hinduism is that I had a bad karma (प्रारब्ध) in past-births. That's why I got hit.
Case B: If instead, I am fortunate enough to be saved, unharmed from bullet fired by my enemy, then the most general explanation given by Hinduism is that I had done some good deeds (प्रारब्ध), which saved me from suffering.
I see a flaw in this reasoning. And the flaw that I observe is that
My past karma (प्रारब्ध) is a function of an external stimuli (enemy here). My enemy's shooting ability is deciding if my past karma to be good or bad.
The paradox: Is my past karma creating a stimulus in my present birth ? Or is the stimulus in my present birth affecting my past karma ?
How can my past karma be changing in accordance with an external stimulus in my present birth ?
Follow-up question: Is human body capable of creating new karma, or is it just to consume the fruits of past karma, or both ?
What are views of Hinduism, in this regard?