Originating from a bit of wordplay involving Lewis Carroll's Alice, it has been referenced in discussions of philosophy, economics, and politics.
[1] This is a pun on a mnemonic[citation needed] for the usage of the Latin word iam (formerly often written and pronounced jam), which means "at this time", but only in the future or past tense, not in the present (which is instead nunc "now").
In more recent times, the phrase has been used to describe a variety of unfulfilled political promises on issues such as tax, and was used by C. S. Lewis in satirizing the extrapolation of evolution from biological theory to philosophical guiding principle, in his 1957 poem "Evolutionary Hymn":[2] Lead us, Evolution, lead us Up the future's endless stair: Chop us, change us, prod us, weed us.
This is not their only quotation from Lewis Carroll, but it reflects their stoic acceptance of straitened means today, and an unquenched hope for better things in some unforeseen tomorrow.
John Maynard Keynes also makes use of the image of "never jam today" in order to portray vividly the tendency to excessive saving which may lead to economic stagnation: For purposiveness means that we are more concerned with the remote future results of our actions than with their own quality or their immediate effects on our own environment.
[3]British folk musician Billy Bragg uses it in his 1986 song "The Home Front": The constant promise of jam tomorrow, Is the New Breed's litany and verse, If it takes another war to fill the churches of England, Then the world the meek inherit, what will it be worth?