Signals, Disclosure, and Persuasion

On 20 May 1875 seventeen states signed at Paris the Metre Convention D [Bureau International des Poids et Mesures 1875; the count of signatories from BIPM's page on the Convention]. Article 1 created a permanent scientific body, the International Bureau of Weights and Measures, at Paris, at the common expense of the parties; Article 3 placed it under the exclusive direction and supervision of an International Committee, itself answerable to a General Conference of delegates of all the contracting governments. Article 6 fixed the Bureau's work: comparisons and verifications of the new prototypes of the metre and the kilogram; custody of the international prototypes; periodic comparisons of national standards with them; comparisons of geodetic, precision and non-metric standards. Article 9 financed it by contributions on a scale based on population. The edition dates each article: Articles 7 and 8 carry the date of the amending convention of 1921, the rest 1875 D [Bureau International des Poids et Mesures 1875, Articles 1, 3, 6, 9].

Field 3 R. In Model S1 and in the worked case below the experiment is a kernel — the probability of a pass in each state — that the receiver knows. The treaty is the institution that makes a kernel common knowledge for physical quantities: a measurement made in one country means the same as one made in another because both are tied, by published comparisons, to one prototype. The two situations above have the same structure: a field called “emissions” is a signal whose kernel is set by a boundary, a method and a verifier, not by the database that stores it.

In 1875 a national standard was compared by bringing it to the prototype: comparability moved at the speed of a physical object and was renewed at the intervals Article 6 calls periodic. A product passport moves a figure in a fraction of a second to anyone with the right to read it. What transmission does not do is what Article 6 did: establish, by procedure, that two figures measure the same thing. The remedy of 1875 was institutional (a bureau, a committee, a conference, a budget rule), not a faster channel, and the accreditation framework and registry above are institutions of the same kind. Computation widens what can be combined and checked; it also lengthens the chain between the reader of a dashboard and the measurement, and the signal is specified only as well as that chain.

A metrology convention is not a strategic-disclosure problem: no party in 1875 chose which measurements to reveal, and the Bureau's duties were comparison, not persuasion. Nor should the present definitions of units be projected back: the convention governs prototypes and their comparison, nothing more.

On 28 March 1895, in a debate in the House of Commons on England and France in Africa, raised on the vote for the Foreign Office, the Under-Secretary for Foreign Affairs, Sir Edward Grey, said that “the advance of a French Expedition under secret instructions right from the other side of Africa, into a territory over which our claims have been known for so long, would be not merely an inconsistent and unexpected act, but it must be perfectly well known to the French Government that it would be an unfriendly act, and would be so viewed by England” D [House of Commons 1895, cols. 405–406]. Three and a half years later a second Blue Book on Fashoda, reported by The Spectator of 29 October 1898 as published that week, included a despatch covering a letter from Major Marchand, who wrote of Fashoda, “which I entered on July 10th last”. On 9 February 1899 Mr Brodrick, answering a question put to the Under-Secretary for Foreign Affairs, told the Commons that discussions were taking place with a view to settling a line of delimitation between the French and Anglo-Egyptian spheres; on 24 March he said that the accounts which had appeared of the agreement between Great Britain and France as to the delimitation of territory in Africa were in the main correct, that he hoped to lay it on the Table in a few days, and that it stipulated for equal treatment of British and French trade between the Nile and Lake Chad D [House of Commons 1899, col. 331; House of Commons 1899, col. 345].

Fields 3 and 4 of Model S6 R. A statement in the Commons is public and recorded, and the same audience can later compare it with what is done; a Blue Book published while a dispute is open puts correspondence on the same footing. In the model these are the moves to which a cost of backing down can attach; a message to which no cost attaches is free talk. The model needs more than the channel: a cost $c$ large enough, and a sender uncertain whether it will be resisted.

The documents of 1895–99 record the channel and the dates, and nothing about $c$: whether any audience would have penalised a retreat, and by how much. A statement made today is recorded and searchable at once and for good, which makes a retreat cheaper to observe. In the model, observation is a precondition of the cost, not the cost: the cost is what an audience does with what it observes, the quantity that survey experiments measure (Tomz 2007).

The box reads documents for their channel. It does not analyse the crisis of 1898, say why any statement was made or published, or claim that the statement of 1895 shaped what followed; no number of the model comes from the record. A historical study that counts the Fashoda crisis among a dozen great-power crises argues that audience costs were not a major factor in any of them (Trachtenberg 2012, pp. 3, 13–17, 32).