3. Complexity and Incommensurability: Multidimensional, Heterogeneous and Interdependent Magnitudes. Probability and Economic Magnitudes

For a comparison between Keynes’s and Sraffa’s philosophy of measure, see Carabelli 2006 and 2018.

Note that Keynes’s 1936 (chapter 12) and 1937 positions are in line with his earlier 1910 analysis in the manuscript notes for the preparation of his lectures on the stock exchange (Notebook, 8 Lectures on Company Finance and Stock Exchange, Lent Term 1910) (Keynes MSS 1910). See Carabelli 2002.

In 1907, he raises the same doubts about the numerical measurement of goodness raised in his 1905 ‘Miscellanea Ethica’:

It may be remarked in this connection that the question, whether every pair of goods are numerically comparable even in respect of goodness, has not received a proper consideration. Many such questions of the greatest importance have hitherto escaped attention, on account of the generally received opinion that all magnitudes, of the same kind prima facie, must necessarily be capable of numerical comparison (PP, 354; see also TP, 345, 349).

As we have seen, for Keynes, probabilities, in general, are neither numerically measurable nor quantitatively comparable save in restricted cases. The calculus of probability and mathematical Benthamite calculus are only applicable in restricted cases. Keynes is in contrast to Moore’s theoretical acceptance of the Benthamite consequentialist calculus, even though Moore in practice rejects it as it is impossible to calculate all the future consequences of action. For Keynes, calculus is unacceptable from the theoretical point of view, given the problems of incommensurability of probability and goodness.

Keynes anticipates the 2009 discussion on whether gross domestic output is an appropriate measure of welfare and happiness of nations (see Stiglitz, Sen and Fitoussi 2009, ‘Report of the Commission on the Measurement of Economic Performance and Social Progress’). Keynes’s argument on happiness and economics is fully investigated in ‘The Economic Problem of Happiness. Keynes on Happiness and Economics’ (Carabelli and Cedrini 2011). Keynes argues that economics only supplies the material preconditions for happiness and full employment is a necessary means to it.

In my 2005 and 2018 articles, ‘Sraffa Versus Keynes on the Method of Economics: Measurement, Homogeneity and Independence’, I compare Keynes’s and Sraffa’s philosophy of measurement (see Carabelli 2005 and 2018).

For a reinterpretation of Keynes’s ‘My Early Beliefs’ and of his ‘religion’, focusing on the religious values of capitalism and Puritanism, Hebraism and Islamism, see Carabelli and Cedrini 2018.

See my 1985 article on ‘Keynes on Cause, Chance and Possibility’ (Carabelli 1985 and also Carabelli 1988).

See my article, written with Cedrini, ‘Chapter 18 of the General Theory “Further Analysed”. Economics as a Way of Reasoning’, for a full investigation of Keynes’s method of reasoning (Carabelli and Cedrini 2014).

On the role of intuition in the General Theory (CW VII, 249): ‘If we examine any actual problem along the lines of the above schematism, we shall find it more manageable; and our practical intuition (which can take account of more detailed complex of facts than can be treated on general principles) will be offered a less intractable material upon which to work’. On animal spirits, see CW VII, Ch. 12.

See also: ‘Let this be agreed on from the start, that every statement concerning matters of practice ought to be said in outline and not with precision, as we said in the beginning that statements should be demanded in a way appropriate to the matter at hand. And matters of practice and questions of what is advantageous never stand fixed, any more than do matters of health. If the universal definition is like this, the definition concerning particulars is even more lacking in precision. For such cases do not fall under any science (techne) nor under any precept, but the agents themselves must in each case look for what suits the occasion, as is also the case in medicine and navigation’ (Nichomachean Ethics 1103b34–1104a10). Martha Nussbaum (1986, especially Ch.10 on ‘Non-scientific deliberation’ and p. 258) points out that the demands of Platonic techne for generality, commensurability and precision were not accepted by Aristotle for ethics.

See Anagnostopoulos 1994, 55–60, 91, 269–270 and especially Ch. 8 on ‘Variation, indefiniteness and exactness’.