The limits of machine ethics

Machine Ethics has established itself as a new discipline that studies how to endow autonomous devices with ethical behavior. This paper provides a general framework for classifying the different approaches that are currently being explored in the field of machine ethics and introduces considerations that are missing from the current debate. In particular, law-based codes implemented as external filters for action - which we have named filtered decision making -are proposed as the basis for future developments. The emergence of values as guides for action is discussed, and personal language - together with subjectivity- are indicated as necessary conditions for this development. Last, utilitarian approaches are studied and the importance of objective expression as a requisite for their implementation is stressed. Only values expressed by the programmer in a public language - that is, separate of subjective considerations - can be evolved in a learning machine, therefore establishing the limits of present-day machine ethics.