The coherence of the Chalcedonian Definition of the incarnation

The definition of the Council of Chalcedon provides the standard orthodox account of the Incarnation of Jesus. This states that the Son, the second person the Trinity, while remaining divine, acquired a perfect human nature (having a ‘rational soul’ and a human body). As Son, he is a spiritual being, having all the divine properties (such as omnipotence, omniscience, perfect freedom, and so perfect goodness). He could only acquire in addition to the divine nature ‘a rational soul’ if that is understood, not as a principle of individuation of the person, but merely as a human way of thinking and acting or (unnecessarily) as an entity which causes the latter. A person can have two separate ways of thinking and acting, the divine and the human, along the lines of a Freudian model in which the person thinking and acting in one way (the human way) is not fully aware of thinking and acting in other way (the divine way). However his ‘perfect humanity’ must be understood in such a way as to involve inability to sin (although compatible with an ability to do less than the best)