The archive.

Split cleanly in two, the Keynesian multiplier here becomes an instantaneous logical ratio implied by the marginal propensity to consume and a dynamic process by which output actually adjusts over time. The first follows at once from how income-receivers divide any increment between spending and accumulation; but that behaviour alone, Shackle stresses, cannot explain why firms would expand the output of consumption goods. Only assumptions about entrepreneurs' reactions to sales, inventories, and expected income turn the ratio into a theory of production. Where earlier writers assumed intended accumulation and realized saving simply coincide, he foregrounds their possible divergence: an attempt to raise the pace of accumulation runs down consumer-goods stocks unless output follows. The open-economy extension folds an export surplus into the same field as domestic investment, so a rising surplus can set expansion going exactly as investment does.

Hitherto in expressing the multiplier principle authors have assumed *equality*.

Can the word 'profit' keep a precise role in economic theory once production is recognized as action stretched through time and shadowed by uncertainty? Shackle's answer is that it cannot serve as one concept, because it silently names two: the imagined inducement that draws an enterpriser into a venture and the recorded result by which the finished venture is judged. Productive services are committed long before the product's exchange value can be known, so contractual payments merely shift uncertainty onto the equity owner rather than abolishing it. Ex ante profit, on this account, is no scalar to be maximized but a configuration of hoped-for gain and feared loss, handled through focus-gain, focus-loss, and the φ-surface. To confuse that conjectural lure with its retrospective outcome, he warns, is an error bred by static, timeless thinking; the argument was spurred by J. A. Stockfisch and J. Fred Weston.

It is only in a static analysis, the description of a situation which is essentially timeless, that a single concept of ‘profit’ could ever be enough.

Before asking how interest-rates are determined, Shackle insists on a prior matter — what interest actually is, and what realities it manifests. His answer breaks with time-preference theory, which presumes agents already know their future, and pushes Keynes's liquidity-preference further by refusing to tame the unknown with probability. Wealth, held for 'possessor-satisfaction' as much as future consumption, may take the form of banknotes, bonds, or equipment; a man who trades banknotes for a bond swaps a known for an unknown quantity of money, and pure interest is the premium for surrendering that certainty. From gain- and loss-epitomes and uncertainty indifference curves the argument builds toward an aggregate model in which saving equals investment by identity, and finally to the British cheap-money drive of 1945–47, where reversing gilt-edged prices betray interest as a manifestation of uncertainty rather than credit standing or thrift.

The rate of interest is, of all prices, the one most inseparably bound up by the logic of its very nature with expectation and uncertainty.

Two rival redrawings of the φ-surface, one by J. Mars and one by H. G. Johnson, prompt this comparison, though the stakes are conceptual rather than merely graphical. Shackle defends a deliberate division of labour: the φ-surface locates the standardized focus-values of a venture, while a separate indifference-map registers the chooser's temperament toward possible gain and loss. Mars's version, by making φ algebraically summable across gains and losses, would let the surface rank ventures on its own and render that map redundant, dissolving the independent representation of an individual's attitude to uncertainty. Through profiles, translated lines, and 'crank-handle' constructions Shackle exposes the cost, and defends his 'subliminal' region, where tiny gains under extreme potential surprise command no attention. Johnson's wooden three-dimensional model he treats more warmly, as suggestive but not decisive.

By abandoning, or drastically circumscribing the role of, the gambler indifference-map, Mr Mars loses an essential ‘degree of freedom’ which my system possesses.

Twenty years after Richard Kahn's 1931 article first set the multiplier out precisely, this survey weighs what that achievement really was. Kahn's originality, Shackle argues, lay less in an unprecedented intuition than in converting a vague, politically urgent idea about public works into a usable analytical instrument, above all by asking when extra spending would raise output rather than prices. He traces three tributaries into the General Theory: Kahn's employment multiplier, Meade's ex post equality of saving and investment, and Warming's insistence that net saving cannot exist without the investment that generates it. Yet the elementary geometric series, he cautions, conceals problems of aggregation, distribution, timing, and expectation. Comparative statics cannot separate past from future or intention from outcome, which is why he sets Hicks's elegant but deliberately non-expectational trade-cycle model against his own expectation-reaction view.

This is the bare bones of the multiplier principle. Its simplicity and ‘obviousness’ are illusory.

The complete economist, on Shackle's mischievous accounting, would need mathematics, philosophy, psychology, anthropology, history, geography, politics, prose, and practical finance all at once—an impossible portrait meant to show that no single technique defines the field. Theory, he argues, is the disciplined imaginative construction of recurrent structures; it grows rigorous not by turning algebraic but by drawing out implications and testing them against rival forms. Keynes stands as proof, since abler mathematicians produced no revolution of their own. From this breadth follows an educational program: recruit able rather than residual students, delay premature specialization, and keep mathematics the servant of economic problems. An economist, on this view, is formed by breadth disciplined into judgment—the capacity to quantify without forgetting the people economics is finally about.

Economics emphatically is about chaps.

Shackle opposes reason to imagination and probability to poetry, without discarding knowledge: business policy, he argues, is an originative art conducted under radical uncertainty, not the solving of a well-posed problem. He builds a scale of openness from dice and cards, which yield a complete list of outcomes, through horse-racing to new enterprise, which has no card of runners and no book of rules. Decision is commitment to a future that does not yet exist, and therefore choice among imagined possibilities rather than known facts. Where probability demands an exhaustive list of contingencies, he substitutes judgments of possibility, surprise, and ascendancy, with focus-gain and focus-loss standing for an enterprise in deliberation. Success, he concludes, needs not only the axial mind that reasons toward a solution but the radial imagination that sees outward into an expanding field of possible histories.

My first proposition is that decision is choice amongst the products of imagination.

One unfinished project links Keynes's Treatise on Money and his General Theory: the attempt to make economics adequate to a future no agent can know. Shackle finds the sharpest tool not in the General Theory but in the Treatise's Fundamental Equations, which he reads as rudimentary sequence analysis—income as anticipated cost, profit as the gap between what was expected and what occurred. From this ex ante/ex post distinction he rebuilds liquidity preference and the marginal efficiency of capital as phenomena of speculative markets, confidence, and mood, not as stable schedules. Economic life becomes kaleidic: neither a march toward equilibrium nor a regular cycle, but a succession of temporary patterns that shifting expectations can shatter in an instant, leaving resources idle as asset-holders retreat into liquidity.

Income, in the Fundamental Equations, is a conjecture which can be wrong.

Thought is the only thing directly known, and its passing is the raw experience from which time itself is abstracted—an unlikely starting point for a theory of choice, and a deliberate one. Shackle builds from it a critique of deterministic economics: if choice genuinely matters, it must be a beginning, an uncaused cause, a taking-place not already implicit in its antecedents, and its sequels cannot be a ready-made list waiting to be ranked. Possibility, for the chooser, becomes the absence of discernible fatal obstacles rather than a measurable frequency; commitment, not calculation, is the vital act, staking self-esteem on imagined outcomes. Marshalling potential surprise, ascendancy, and focus-gain against frequency probability, he makes investment the exemplary economic act—a symbolic wager on a future whose outcomes can never be exhaustively listed.

Possibility, for the chooser, is the absence of discernible fatal obstacles.

The alternatives among which a person chooses are creations of his own thought, not a menu the world hands down — and from that premise Shackle builds this compact statement of subjectivist economics, written to introduce Alexander Shand's survey of the tradition from Plato to Hayek. Choice becomes creative rather than calculative, its consequences unknowable in advance, so that the future is not merely unknown but partly made. Non-determinism and the unpredictability of history-to-come follow, along with a political corollary: central coercion cannot render human affairs predictable, only extinguish the dispersed invention that renews economic life. Markets earn their place by disseminating knowledge after events occur, never by abolishing uncertainty.

Subjectivism credits the individual with the power of the alchemist who can throw into his crucible whatever his fancy has invented but knows not what will emerge.