Not only does man develop his essence daily, but so does the world. Both are open-ended. If an Existentialist believes in God, he believes that God's world is open-ended because God is still busy creating. Existentialism and Experimentalism agree on open-endness, the quality of contingency, and the element of nothing given beforehand. However, when attacked, Experimentalism has always retreated to Science for shelter.
Existentialism looks for no shelters.
The sky is open. Existentialism and Experimentalism stand apart from Idealism, Realism, and Rationalism because they posit to reality no absolute or necessary qualities standing outside of and independent of human knowing. In these two philosophies reality is, in one way or another, man-made. Existentialism rejects the physical world of things and the Platonic world of transcendental ideas as ultimate. Reality originates in the inner self of man because it is here that man first discovers himself before anything else.