Introduction

In this chapter, I would like to explore a connection between Wittgenstein's Lecture on Ethics (Wittgenstein 1965: LE) and the ethics of Artificial Intelligence (AI ethics). Part of the project in AI Ethics is pursued by attempting to provide a formal account of a group of interrelated concepts determining what von Wright (1951), in a seminal article on the subject, called modes of obligation. Amongst such concepts, dubbed deontic by von Wright, are: the obligatory (what ought to be done); the permissible (what is allowed to be done); and the forbidden (what must not be done).

Since von Wright's paper, it has become standard to treat deontic concepts as forming a distinctive class of modalities in addition to other perhaps more familiar such classes. An obvious example comprises alethic (or sometimes metaphysical) modalities, represented in language by what are known as the modes of truth: what cannot but be the case; what can be the case; and what cannot be the case.

Prima facie, the classes of deontic and alethic modalities respectively single out two ways in which we could use language: normatively, to express obligations (and cognate notions); and descriptively, to express necessities (ditto). The Lecture on Ethics is the only place in which Wittgenstein elaborated on the relationship between normative and descriptive uses of language, at any length. In it, as is known, Wittgenstein joins a tradition stretching back at least to Hume in maintaining that no normative claim could ever logically follow from a descriptive claim; an ‘is’ can never entail an ‘ought’. What is perhaps less known is that the thesis defended by Wittgenstein in the Lecture on Ethics might have an important role to play in debates around the existential risk posed by the rapid development of AI.

This chapter has thus a twofold goal. In the first section I would like to show how, by accepting the thesis that an ‘is’ never entails an ‘ought’, the strength of some arguments purporting to show that AI poses an existential threat appears rather dim. In the second section, I would like to propose my own reading of Wittgenstein's arguments in favour of the no-‘ought’-from-an-‘is’ thesis, put forward in the Lecture on Ethics.