 abstract objects |  Brouwer, Luitzen Egbertus Jan |  dependence, ontological |  epsilon calculus |  existence |  logic: intuitionistic |  logic and ontology |  mathematics, philosophy of |  mathematics, philosophy of: fictionalism |  mathematics, philosophy of: formalism |  mathematics, philosophy of: indispensability arguments in the |  mathematics, philosophy of: nominalism |  mathematics, philosophy of: structuralism |  mathematics: constructive |  mathematics: explanation in |  mathematics: non-deductive methods in |  naturalism |  nominalism: in metaphysics |  object |  ontological commitment |  Platonism: in metaphysics |  Platonism: in the philosophy of mathematics |  Quine, Willard van Orman: New Foundations |  realism |  realism: challenges to metaphysical |  reism |  scientific realism |  set theory |  set theory: early development |  structural realism |  truth |  type theory |  Wittgenstein, Ludwig: philosophy of mathematics 