Die Existenz von zwei Arten ist eigentlich eine Tatsache, welche seit langem bekannt ist: Eine Tatsache, welche in der einen oder anderen Form dem Beobachter der menschlichen Natur klar geworden ist oder die brütende Reflexion des Denkers beleuchtete
— Carl Jung, Introduction to Psychological Types, page 11 (1923 English translation)

One of the great problems of history is that the concepts of love and power have usually been contrasted as opposites, polar opposites, so that love is identified with a resignation of power, and power with a denial of love Now we got to get this thing right. What is needed is a realization that power without love is reckless and abusive, and that love without power is sentimental and anemic.
— Martin Luther King Jr. Where Do We Go From Here? "Philosophers have only interpreted the world in certain ways; the point is to change it". — Karl Marx, 11th Thesis on Feuerbach

"The philosopher should say to the activist something like the following. To change the world is not necessarily to improve it. To improve it is to make it better. For this two things are required. First, one must understand the world and the people in it both as to what they actually are and as to what they are capable of. In particular, one must possess a sound understanding of human nature. Second, one must know how things objectively ought to be. Can the various activists and world-improvers claim to know these two things? Well, they can claim to know them, but not with any show of legitimacy. Truly ameliorative praxis must be based on sound theory concerning what is and what ought to be, and this alone philosophy can provide — if anything can provide it I suggest we turn Marx on his head: The activists have variously tampered with the world, often with horrendous results; the point, however, is to understand it." — William F. Vallicella

What if both these views are valid?

Die Vorstellung, daß nicht alle Menschen nach dem gleichen Grundriss gebaut sind — daß es möglicherweise zwei menschliche Naturen gibt statt einer, — hat die Philosophie seit den Griechen verfolgt. In der Tat, was wäre, wenn es drei oder mehr, grundlegende Charakter-Typen gäbe?

Die Literatur der modernen Psychologie ist voller amüsanter Spekulationen in diesem Bereich, aber nur wenig davon kann ernst genommen werden. Die klassischen Ausnahmen sind James und Jung, auf beide wird in der unten genannten Bibliographie eingegangen. In den folgenden Links finden Sie außerdem einen Überblick über die grundlegende Semantik Pauls, einen Zeitstrahl der Polaritätstheorie, und eine Auswahl der interessantesten Zitate aus historischen Quellen.