In other words, the fundamental principles and indispensable postulates of every genuinely productive science are not based on pure logic but rather … - Max Karl Ernst Ludwig Planck

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In other words, the fundamental principles and indispensable postulates of every genuinely productive science are not based on pure logic but rather on the metaphysical hypothesis — which no rules of logic can refute — that there exists an outer world which is entirely independent of ourselves. It is only through the immediate dictate of our consciousness that we know that this world exists. And that consciousness may to a certain degree be called a special sense.