 analysis |  descriptions |  facts |  Frege, Gottlob |  logical constructions |  Moore, George Edward |  Ockham [Occam], William |  Principia Mathematica |  propositional function |  propositions |  Russell, Bertrand |  sense data |  simplicity |  Vienna Circle |  Wittgenstein, Ludwig |  Wittgenstein, Ludwig: logical atomism 