text: The first person to recognize this, to my knowledge, was John Maynard Keynes is his gorgeous, but now little read, A Treatise on Probability , a book which argued that all probability statements were statements of logic To Keynesand to usall probability is conditional; you cannot have a probability of A, but you can have a probability of A with respect to certain evidence. Change the evidence and change the probability of A. Stating a probability of A unconditional on any evidence disconnects that statement from reality, so to speak.