I wouldn't be so sure about that. Granted, Schopenhaur warmed to elements of Eastern thinking finding unexpected similarities with his own, but he regarded Indian notions of karma as being a subtle use of myth and metaphor rather than reality; in his own words he referred to reincarnation as the myth of the transmigration of souls. Having myths and metaphors is fine, but the karmic myth results in defacto harm to many vulnerable people who need support and understanding not prejudice and isolation.
https://en.wikipedia.org/wiki/Arthur_Schopenhauer********
Schopenhauer read the Latin translation of the ancient Hindu texts, The Upanishads, which French writer Anquetil du Perron had translated from the Persian translation of Prince Dara Shikoh entitled Sirre-Akbar ("The Great Secret"). He was so impressed by their philosophy that he called them "
the production of the highest human wisdom," and believed they contained superhuman concepts. The Upanishads was a great source of inspiration to Schopenhauer. Writing about them, he said:
It is the most satisfying and elevating reading (with the exception of the original text) which is possible in the world; it has been the solace of my life and will be the solace of my death.[89]
It is well known that the book Oupnekhat (Upanishad) always lay open on his table, and he invariably studied it before sleeping at night. He called the opening up of Sanskrit literature "the greatest gift of our century," and predicted that the philosophy and knowledge of the Upanishads would become the cherished faith of the West.[90]
Most noticeable, in the case of Schopenhauer’s work, was the significance of the Chandogya Upanishad, whose Mahavakya,
Tat Tvam Asi is mentioned throughout The World as Will and Representation.
Concerning the Upanishads and Vedas, he writes in The World as Will and Representation:
If the reader has also received the benefit of the Vedas, the access to which by means of the Upanishads is in my eyes the greatest privilege which this still young century (1818) may claim before all previous centuries, if then the reader, I say, has received his initiation in primeval Indian wisdom, and received it with an open heart, he will be prepared in the very best way for hearing what I have to tell him. It will not sound to him strange, as to many others, much less disagreeable; for I might, if it did not sound conceited, contend that every one of the detached statements which constitute the Upanishads, may be deduced as a necessary result from the fundamental thoughts which I have to enunciate, though those deductions themselves are by no means to be found there.
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No one can be so highly influenced by Hindu philosophy without accepting Karma and reincarnation because they form the foundation of Hinduism.
You wanted some western philosophers and I have given you. There is a thread on Tat Tvam Asi in the Eastern section.