  It is argued that there is no evidence for causality as a metaphysical
relation in quantum phenomena. The assumption that there are no causal laws,
but only probabilities for physical processes constrained by symmetries, leads
naturally to quantum mechanics. In particular, an argument is made for why
there are probability amplitudes that are complex numbers, which obey the Born
rule for quantum probabilities. This argument generalizes the Feynman path
integral formulation of quantum mechanics to include all possible actions that
are allowed by symmetries, but only the lowest order terms are observable at
the presently accessible energy scales. The notion of relational reality is
introduced in order to give physical meaning to probabilities. This appears to
give rise to a new interpretation of quantum mechanics.
