A defense of Ontological Realism without commitment to Epistemic Realism

Scientific realism is viewed as the conjunction of three theses – a metaphysical, a semantic and an epistemic claim. Logical positivists as the dominant empiricist approach in the first decades of twenty century rejected these triple viewpoints in order to remove metaphysics from the realm of science. In the framework of Constructive Empiricism, van Fraassen, by having the same aim, and by introducing observables/unobservables distinction, accepts the realists’ semantic view, but unlike realists, he defends epistemic and also ontological distinction between observables and unobservable theories/ entities. In this paper, we try to defend epistemic observable/ unobservable distinction while rejecting ontological observable/ unobservable distinction based on some doctrines in Mulla Sadra’s philosophy and defend a kind of ontological realism, namely Existential Realism. To reach this aim, we first explain observable/unobservable distinction as the foundation of Constructive Empiricism and the main objections to it. Then, by briefly explaining Mulla Sadra's Existentialism, we will show that van Fraassen's epistemic antirealism viewpoint is compatible with Mulla Sadra's ontological realism approach.