Sidgwick

The Cambridge School of Economics was undoubtedly created by Marshall. However, ‘it was not created by Marshall alone’, as behind Marshall ‘was Sidgwick...Marshall’s “spiritual father and mother”’ (Backhouse 2006: 40). As Sidgwick did not write a major work on psychology, his interest in it was indirect rather than direct, but this does not mean that it was unimportant. For example, he wrote an article on ‘Idiopsychological Ethics’ for Mind (Sidgwick 1887), and his philosophy was sometimes linked to that of Ward (Keynes 1936: 589).

Sidgwick had studied the origins of psychology as trends in Continental philosophy, and his work on this topic illustrated some common Cambridge themes. For instance, he disagreed with Kant’s rational psychology as containing a ‘fundamental misapprehension of the knowledge of self which we obtain through self-consciousness’ (Sidgwick 1905: 144). Instead of asserting the idea that rational psychology obtained synthetic truths a priori, Sidgwick argued that a rigid separation between rational and empirical psychology was ‘unthinkable’ (ibid.: 148). He declared that the ‘existent we’ could not conceive itself as other than an existing object:

[A]ll the particularity of the mind, all that interests us in our thought of ourselves and other minds as relatively permanent objects of thought. we only know by inference from the transient and ever-varying element of inner experience ... I still know myself as one and identical, perduring through the empirical stream of thoughts, feelings, and volitions (ibid.: 150—151; italics in original).

Put simply, inner self could only be conscious in relation to some external and changing reality or empirical experience. Sidgwick thus disagreed with Kant’s dualistic soul/body distinction, but at the same time he recognised the limitations of the associationist psychology that was used by Mill (Sidgwick 1904: 166, 169).

What significance did this disagreement have for Cambridge economics? One answer related to Sidgwick’s use of the idea of evolution, which posited the notion of an ‘external and changing reality’ as being determinate, and distinguished between different concepts of evolution and their relevance to the theory of rational conduct. More controversially he gave validity to nonrational or psychological forms of reasoning as they had evolved as habits and emotions, as against assuming that conscious ‘rational’ calculation always produced a superior result:

[W]hat ought we to do when Moral Sentiment comes into conflict with the conclusions of Rational Utilitarianism? Granting that both are really akin and spring from the same root, which ought we to obey, Reason or Instinct? ... [O]ur power of calculating pleasures and pains is so imperfect as to make it really rational in the pursuit of happiness, to disregard the results of conscious calculation when they are clearly in conflict with any of these embodiments of unconscious reasoning and outgrowths of ages of experience (Sidgwick 1876b: 66).

On the other hand, Sidgwick suggested that practical reason was itself an adaptation of the evolved organism to its circumstances, and thus ‘if Instinct is really implicit (utilitarian) reason, it is better to perform the calculation explicitly’. Sidgwick’s final position, albeit only implicitly rendered, was that neither reason nor instinct should be given a privileged status in deciding which should be followed in any instance—‘a plausible case may be made out for either’ (ibid.)—as both had proved to be fallible.

Sidgwick evidently understood that mental calculation was a complex phenomenon involving both conscious and instinctual components. An evolutionary account of reason therefore provided no case for or against any ethical doctrine as a basis for right conduct, as reason itself progressed over time. In going beyond a purely ‘physicalist’ approach to understanding mental phenomena, instead positing a complex interaction, Sidgwick was foreshadowing the criticisms of associationism that were articulated at Cambridge by Ward (Cook 2006; Sidgwick 1876b: 54).

How did this rejection of a purely ‘conscious’ understanding of rationality influence Sidgwick’s economics? For one thing it made him more open to a nonindividualistic understanding of behaviour. In an essay on economic methodology, he presaged (albeit loosely) a fundamental proposition of contemporary evolutionary biology—inclusive fitness—indicating that the individual maximization approach to explaining behaviour required modification. Sidgwick explained that ‘ordinary economic man is always understood to be busily providing for a wife and children; so that his dominant motive to industry is rather domestic interest than self-interest, strictly so-called’ (Sidgwick 1885: 29).

By ‘domestic interest’ he meant ‘family interest’, that is, what evolutionary biologists today call inclusive fitness (the interests of an individual’s close family taken as a group), rather than the solitary individual’s self-interest ‘strictly so-called’ taken alone (Buss 2004: 14, 221). In ‘Idiopsychological Ethics’, Sidgwick considered a series of different motives that underpinned human behaviour as a hierarchy of operations, including passions, affections, and sentiments: the ‘love of gain’, categorised as a reflective derivation from appetite, was only one among many (Sidgwick 1887: 42). It is thus evident that he recognised a wider range of rationalities than is sometimes considered as purely economic, and psychological factors were part of this wider scheme.