Existential Realism on Trial II - A Series of Critical Q&A Stress-Tests: Asymmetry, Modality, Relativity, Quantum, Phenomenology

This paper critically evaluates Existential Realism (ER) by testing whether its distinctive ontology of present instantiation provides genuine explanatory advantages over block-based accounts of spacetime. Rather than asking whether ER is conceptually distinguishable from eternalism or structural realism, the analysis focuses on a stronger criterion: explanatory necessity. Five domains commonly invoked in debates about temporal ontology are examined as diagnostic tests—relativity, modal openness of the future, thermodynamic asymmetry, the ontological status of the past, quantum actualization, and temporal phenomenology. In each case the central question is whether ER explains the relevant phenomena more effectively than a block ontology supplemented with standard physical or probabilistic structure. The analysis finds that while ER offers a coherent framework that aligns naturally with certain intuitions about temporal becoming, its explanatory advantages remain unclear. Many of the phenomena ER aims to illuminate can be accounted for within block-based models without introducing additional ontological primitives. The result is not a refutation of ER but a reframing of the debate: the key challenge for ER is to demonstrate a domain in which the ontology of becoming delivers explanatory leverage that cannot be replicated by block ontology. Until such advantages are clearly articulated, the explanatory economy of block-based accounts remains a significant competing consideration.