I find Lucien Hardy's discussion enlightening: Quantum Theory From Five Reasonable Axioms https://arxiv.org/abs/quant-ph/0101012 https://arxiv.org/abs/quant-p

I find Lucien Hardy's discussion enlightening: Quantum Theory From Five Reasonable Axioms https://arxiv.org/abs/quant-ph/0101012 https://arxiv.org/abs/quant-ph/0101012