According to wikipedia ref here
...The philosophy of karma is closely associated with the idea of rebirth in many schools of Indian religions (particularly Hinduism, Buddhism, Jainism and Sikhism)..
The idea Karma has received criticising on the western world because it seems to be a flawed theory from a religious and philosophical point of view because it collides with concepts such us existential justice, psychology and free will. It is said it's just a purely religious concept just like "original sin" in the Christian religion with no basis on reality created to justify the socio-political status quo in some countries.
Examples of key questions:
How ethical would be to pay for something you don't remember doing based on hypothetical non-provable past-life experiences? Is it justified for an slave to be born a slave under the pretext of bad karma?
Why would existence be so cruel to remove all my knowledge lifetime after lifetime and make me need to learn to talk, walk, behave, etc. and make suffer to gain more knowledge reincarnation after reincarnation?
If my parents give me a cruel upbringing or I am raised to be a criminal how would that affect my karma? If i'm bipolar or with anger management issues how will I be punished by karma?
Could it be that Karma is just an illusory concept created by an evil demon that wants your freewill to reincarnate over and over again? If gods can create illusory worlds (Maya) and can remove your knowledge life after life why do I have to trust them when they tell me that I did cruel things in previous lives? Is not that a paradox?
Some monks and yogis state that the human mind is not capable of fully understanding Karma because it operates in multiple dimensions and in different layers of space/time. In the Yoga sutras just like and time and ego and other tattvas are creations of the mind or illusory in nature therefore you must eventually detach from them to discover your true self.
I'm looking for references to authors who critique on Karma or give a better understanding of it.
BG 14.6: Amongst these, sattva guṇa, the mode of goodness, being purer than the others, is illuminating and full of well-being. O sinless one, it binds the soul by creating attachment for a sense of happiness and knowledge.