into three questions. The Existence Question: is there progress in philosophy? The Comparison Question: is there as much progress in philosophy as in science? The Explanation Question: why isn't there more progress in philosophy?[4] Realism Does a world independent of human beliefs and representations exist? Is such a world empirically accessible, or would such a world be forever beyond the bounds of human sense and hence unknowable? Can human activity and agency change the objective structure of the world? These questions continue to receive much attention in the philosophy of science. A clear "yes" to the first question is a hallmark of the scientific realism perspective. Philosophers such as Bas van Fraassen have important and interesting answers to the second question. In addition to the realism vs. empiricism axis of debate, there is a realism vs. social constructivism axis which heats many academic passions. With respect to the third question, Paul Boghossian's Fear of Knowledge: Against Relativism and Constructivism is a powerful critique of social constructivism, for instance. Ian Hacking's The Social Construction of What? constitutes a more moderate critique of constructivism, which usefully disambiguates confusing polysemy of the term "constructivism." Relationship between science and religion What is the relationship between science and religion? Philosophers like Paul Feyerabend, A. C. Grayling, and Alvin Plantinga have debated whether they are in conflict, incompatible, incommensurable, or independent. Philosophy of religion Philosophy of religion encompasses attempts within metaphysics, epistemology, ethics, and other major philosophical fields to philosophically analyze concepts within religion, the nature of religion itself, and alternatives to religion. Existence of God Does God exist? A rich variety of arguments including forms of the contingency argument, ontological argument, and moral argument have been proposed by philosophers like Aristotle, Descartes, Leibniz, Gödel, and Aquinas for the existence of God throughout history. Arguments for God usually refer to some form of metaphysically or logically necessary maximally great being distinct from individual deities, although philosophers have also proposed different concepts of God. Wittgenstein and Kant, on the other hand, defended religious belief while doubting that rational arguments could prove God's existence. Philosophers have also considered objections to the existence of God like the problem of evil and divine hiddenness. Nature of God What is God like? Philosophers like John Stuart Mill and Aquinas addressed the question of what the nature of God is if God exists. Some of the key disagreements concern the doctrine of