The Steel Crocodile (1970) by D G Compton

In answer to an unanswerable future, science has created Bohn, the omnipotent computer whose flashing circuits and messianic pronouncements dictate what tomorrow will - or will not - be.

But Matthew Oliver is flesh and blood and full of questions - not nearly as certain as the machine he's appointed to serve.

And the right hand of science seldom knows what the left hand is doing . . .