Decisions, decisions, the problem of undecidability and calculative reasoning

Derrida characterises the problem of undecidability as follows: “However careful one is in the theoretical preparation of a decision, the instant of the decision, if there is to be a decision, must be heterogeneous to the accumulation of knowledge. 

Otherwise, there is no responsibility... the decision, if there is to be one, must advance towards a future which is not known, which cannot be anticipated”