The trusting Yes in principle to uncertain reality is not supported by any external rationality. I cannot establish objectively, as it were from outside, the foundation of my positive fundamental attitude. To begin with, there is nothing that can be shown to be obvious or reasonable that might, then, guarantee the foundation of my trust and make it beyond all doubt. There simply is nothing of this kind, nothing that could be assumed as the Archimedean point of thought.
For, since it is a question of reality as a whole – that is, of the totality of all that exists – outside which there is nothing but nothingness itself, all external arguments are ruled out. And any attempt at a rational demonstration of the Yes in principle to the fundamental reasonableness of my reason implicit in the Yes to reality can end only in a vicious circle. The reasonableness of reason can actually be accepted only in a resolute trust, to which there is always the alternative of fundamental mistrust.
The trustful Yes in principle to uncertain reality is distinguished by an intrinsic rationality. I can experience the firm foundation of my fundamentally positive attitude to reality. For reality manifests itself throughout all uncertainty and permits my fundamental trust in it (not blind confidence) to be seen as justified. In other words in my very trust in being – which is not mere credulity – in the midst of all the real menace of the nullity of beings I experience being and with it the fundamental justification of my trust.
Likewise in my trust in reason – which, again, is not credulity – and in the confident use of reason, despite all the real menace of unreason, I experience the fundamental reasonableness of reason. Like other basic experiences (for example, love and hope), the basic experience of trust is apparent only in its realization, through practice. It is only in the realization that I experience the justification of my Yes to (persistently uncertain) reality.
What is directly helpful is only trust practiced by each person for himself and continually undertaken afresh. However useful the theories and however helpful exercises on dry land may be, I can learn to swim only in the water: I must take the not irrational but utterly rationally justifiable risk and commit myself to the insecure watery element that will sustain me if I allow myself to be sustained.
“Similarly, against nihilism, living testimony to reality can be indirectly helpful. If another person despite all uncertainty says Yes to reality and lives out convincingly his positive fundamental attitude, he can rouse in me a willingness for the same fundamental trust. The risk taken by the other person is an invitation to me to take the same risk, just as the person who jumps first into the water shows that it will also sustain me. Of course each individual must himself swim. The risk undertaken by the other person does not relieve me of taking my own risk.”
From “Does God Exist?” by Hans Kung