The Eleatic dictum isn’t the whole truth about reality. There could be real things that have no causal powers. Maybe numbers are real without having causal powers, for example. Maybe there could be a forgotten dream with no causal powers. But causal powers provide at least a sufficient condition for reality. If something has causal powers, then it exists and it is real. In this way, causal powers add a second heuristic criterion for something’s being real, alongside existence itself.
