Definition
Promised benefits that never arrive.
The availability of a resource at a future date.
Origins
From Lewis Carroll's Through the Looking-Glass (1871), where Alice is offered “jam to-morrow and jam yesterday — but never jam to-day”. This is a pun on a mnemonic for the usage of jam, iam in Latin (note i/j conflation in Latin spelling), which means “now”, but only in the future or past tense, not in the present (which is instead nunc).
In Context
- "The “purposive” man ... does not love his cat, but his cat’s kittens; nor, in truth, the kittens, but only the kittens’ kittens, and so on forward forever to the end of cat-dom. For him jam is not jam unless it is a case of jam to-morrow and never jam to-day."
- "Yet they've proved that common men can show astonishing fortitude in chasing jam tomorrow."
- "It always seems to be a problem to be dealt with when resources (later) permit. Jam tomorrow, as usual."
- "The consumption-possibilities curve illustrates the choice which must be made: more jam today means less jam tomorrow; less jam today means more jam tomorrow."
- "A basic human characteristic is the preference for consumption today over consumption tomorrow. Jam today is always better than jam tomorrow, unless sufficient incentive is offered to forgo the immediate enjoyment of today's jam. This is not because of uncertainty about the likely receipt of tomorrow's jam, but merely a property of the passage of time."
- "For one-period optimization, the obvious course of action to maximize consumption is to consume the whole of output by “eating up” the capital stock. The inapplicability of this tactic to an industrializing nation is transparent—it gets a lot of jam for today but leaves little for tomorrow. Jam today has therefore to be balanced against jam tomorrow."