The archive.

A small revision in expectations can provoke a large shift from money into speculative assets. In this 1945 article, G. L. S. Shackle asks how that disproportion arises when investors confront imagined possibilities rather than a certain forecast. His distinctive vocabulary—“potential surprise,” “focus gain,” and “focus loss”—connects the outcomes that capture an investor’s attention with the gains and losses that investor is willing to contemplate. Geometrical models show how purchases can raise prices and seemingly confirm the optimism that prompted them. Development land provides a revealing test: each owner may plausibly anticipate a profitable sale even when all those hopes cannot be fulfilled together. The article offers a precise way to examine how individually credible possibilities can sustain collectively incompatible valuations, while exposing the assumptions behind its own account of portfolio choice.

Gunnar Myrdal's 1933 essay on monetary equilibrium deserves, Shackle argues, a recognition equal to anything in interwar economics, and he reconstructs it to show why. Myrdal's achievement was to reset Wicksell's problem in time: the natural rate cannot be the observable yield on existing capital, since that yield, once the stream of expected net receipts is discounted at the current interest rate, is tautologically tied to it. The live variable is instead the gap between a projected plant's capital value and its construction cost, a valuation formed before building and therefore a matter of expectations. Equilibrium is recast as compatibility among plans, read alongside Hayek: not balanced aggregates but a state in which realized events force no one to remake their anticipations. Even aggregate equality of investment and 'waiting', Shackle shows, can conceal offsetting individual errors.

Monetary equilibrium in this meaning is a means of classifying the set, considered as a whole, of systems of expectations which are entertained, one system by each individual, at some one point of time.

Orthodox theory said a fall in interest-rates should quicken investment by raising the present value of future returns; businessmen questioned by the Oxford Economists' Research Group flatly denied noticing any such effect. Rather than discard the doctrine, Shackle narrows it. A future receipt must be discounted twice, once for deferment through the pure interest rate and once for doubt, and the two work very differently: interest bites hardest on distant, secure returns, which is why housing and other long-lived, dependable assets remain rate-sensitive. But where invention, fashion, and obsolescence truncate an asset's useful life, a swelling 'marginal rate of risk' absorbs the far future before the pure rate can act, leaving valuations almost unmoved by a one-point change. Entrepreneurs, attending to shifting orders and markets, simply never register interest as the cause of their decisions.

It was until recent years an accepted doctrine that changes of interest-rates powerfully influence the pace at which enterprisers, all taken together, extend or improve their equipment.

Preventing depression without making economic security depend on compulsory controls is the tension at the centre of Shackle’s 1947 review of William J. Fellner’s Monetary Policies and Full Employment. Shackle examines Fellner’s distinction between timely action against recession and an unconditional employment guarantee that could encourage inflationary wage and price demands. His particular interest lies in uncertainty: larger expected profits need not be more dependable, and lower wages need not improve investment prospects. This compact review lets readers see why the composition and reliability of demand matter alongside its volume. Shackle’s approval remains discriminating: he praises Fellner’s practical judgement while challenging an interest-rate analysis that, in his view, confuses planned and realised quantities, stocks and flows.

Once the Exchequer acquires a duty to stabilize aggregate demand, the old arithmetic of matching revenue to authorized expenditure no longer suffices. Written in 1947 in the wake of Keynes, this essay treats every fiscal stream as a force acting on monetary demand relative to the supply of goods, and builds a pair of indices—deflative P and inflative Q—to measure the initial thrust of a specified receipt or disbursement before secondary reactions unfold. Shackle's taxonomy of pensioners, policemen, postmen, palace-builders, and paper-makers shows why a payment that adds no saleable output pushes prices up while a purchase for resale may prove deflative. A tax label alone, he insists, never fixes the direction of pressure; only the composition of spending does.

The Exchequer, in deciding the size, method and timing of its levies and disbursements, must nowadays be guided by two quite distinct sets of considerations.

A move in chess reshapes the whole board; so, Shackle insists, does a genuinely crucial economic decision, one that cannot be repeated because it alters the very conditions under which any later choice would occur. Replying here to critics of Expectation in Economics, he defends the distinction between unique, isolated, and crucial trials against those who would treat rival imagined futures as additive terms in a single statistical expectation. Mutually exclusive outcomes, he argues, cannot be summed like fractions drawn from an urn; the chooser confronts an act, a moment, and a set of hypotheses. Against Baumol and Graaff he deploys his focus-value method, the φ-function, and potential surprise, rejecting 'degree of belief' as any general rescue of probabilistic ordering.

Now when an experiment, a question about the future, is unique, isolated, or crucial, it does not make sense to add together its rival hypothetical outcomes or answers.

Numerical probability divides a fixed unit of belief among rival hypotheses; that additive structure, Shackle contends, is exactly what makes it useless for describing genuine uncertainty, where several incompatible outcomes may each be perfectly possible with nothing known against them. The remedy proposed is potential surprise, a non-additive measure of disbelief that lets rival hypotheses coexist without competing for a common total. Dividing experiments into 'divisible' series, where frequency ratios can render an aggregate outcome knowable in advance, and unique 'non-divisible' acts, where such ratios are meaningless, he weighs an integrative decision rule, drawn via Ralph Turvey from Ingvar Svennilson, against his own focus-values solution and rejects the former as psychologically artificial. Expectation, he concludes, is an act of creative imagination, not rational calculation on incomplete data.

For a non-divisible, unique experiment it is plain that no frequency-ratio can have any meaning or relevance.

An investment cannot always be treated as one trial in a repeatable gamble. How, then, can an economist analyse a decision whose consequences may be unique? Shackle locates its motives in present experiences of imagined futures: the gains that excite hope and the losses that command fear. His alternative to numerical probability, “potential surprise,” measures how astonishing an outcome would seem rather than assigning it a share of total likelihood. The resulting model offers a striking account of waiting: an investor may postpone commitment because information is coming, even without knowing what it will say. Readers can examine both the explanatory reach and the psychological demands of a theory in which two compelling possibilities—not an average across all outcomes—govern a venture’s attraction.

A Chinese sentry, Kwong Hui, weighs loyalty against treachery in a choice he can make only once — and for whom, as Shackle drily observes, a severed head is rather final. From Keith West's parable Shackle draws his standing objection to orthodox decision theory: frequency-ratio probability describes a series of repeatable trials, but says nothing about the single occasion whose outcome absorbs a person's whole future. Such crucial experiments may destroy the very conditions under which they were run, so they cannot be rerun. In their place he offers not calculation but imaginative appraisal, where rival hypotheses are ranked by their power to stir hope or fear and by their degree of potential surprise, and choice settles on a representative focus-gain and focus-loss. It is a founding statement of the Knight–Keynes–Shackle line dividing calculable risk from genuine uncertainty.

For a non-divisible non-seriable experiment the concept of frequency-ratios is wholly irrelevant.

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.

Statistical agreement does not necessarily tell us which economic relationship has been measured. In this 1951 review of Lawrence R. Klein’s Economic Fluctuations in the United States, 1921–1941, G. L. S. Shackle pairs enthusiasm for econometrics with a precise account of its limits. He values its power to expose ambiguities in theory and distinguish consequential relationships from negligible ones, yet shows how a simple consumption–investment model can produce two apparently similar equations with different underlying parameters. His perspective is neither a defence of purely deductive economics nor an unqualified endorsement of empirical modelling: internal coherence is not evidence, but estimation does not guarantee structural knowledge. This short review makes the identification problem accessible while revealing why Shackle found Klein’s methodological candour as valuable as his technical achievement.