The most important thing in life is to stop saying 'I wish' and start saying 'I will.' Consider nothing impossible, then treat possiblities as probabilities.
Presumption means nothing more than as stated by Lord Mansfield, the weighing of probabilities, and deciding, by the powers of common sense, on which side the truth is.
Ignorance gives one a large range of probabilities.
It is impossible to trap modern physics into predicting anything with perfect determinism because it deals with probabilities from the outset.