The Project

The XPHI project is funded by the Arts and Humanities Research Council. It ran from October 2014 to January 2017 and it is based at the universities of Warwick and Sydney.

The project has two aims:

  • to improve our understanding of early modern experimental philosophy.
  • to assess the viability the methodological outlook underpinning early modern and recent attempts to build an empirical science of ethics.


One of the most prominent current trends within philosophy is represented by the attempts to naturalize philosophical disciplines, from epistemology to ethics, and to tackle their problems with the tools of empirical sciences. An analogous naturalistic trend was prominent between 1660 and 1800. In this period, a large group of self-proclaimed experimental philosophers promoted an approach to the study of the natural world, ethics, and aesthetics which was based on the rejection of substantive a priori claims and the reliance on extensive observation and experimentation.

Initially, Robert Boyle, John Locke, members of the early Royal Society and like-minded authors in France and Italy applied this approach to empirical issues within physics and medicine and to metaphysical questions concerning, for instance, the nature of causation and the basic structure of the material world. Later experimentalists extended their rejection of ‘first philosophy’ and application of empirical methods to the fields of ethics and aesthetics. Scottish and German authors, like David Hume and J. G. H. Feder, advocated the ‘application of experimental philosophy to moral subjects’ (Hume) and relied on empirical claims to promote sentimentalist ethical theories.

Nowadays, many ethicists endorse the same methodological outlook of eighteenth-century experimental philosophers, claiming that we should study morality with methods ‘suitable to the investigation of natural facts’ (Jesse Prinz). We are told that the results of fMRI scans refute deontologism (Joshua D. Greene, Peter Singer), that experimental psychology refutes moral intuitionism (Walter Sinnott-Armstrong) and virtue ethics (Gilbert Harman, John Doris), and that Humean moral sentiment derives from oxytocin, ‘the moral molecule’ (Paul J. Zak, Patricia Churchland). Along similar lines, a wave of popular books by well-known primatologists, evolutionary biologists, psychologists, and neuroscientists advocates the replacement of armchair ethics with an empirical ‘science of morality’ (Sam Harris), ‘the science of good and evil’ (Michael Shermer), ‘the science of our moral dilemmas’ (Michael S. Gazzaniga), and so on.

Research questions

A. Early modern experimental philosophy and substantive a priori commitments:
  1. Experimental philosophy purported to be a ‘second philosophy’ that did not rely on the ‘first’ – on substantive a priori claims and theories on the world. Was it really uncommitted to a priori metaphysical assumptions, or did it only replace the old dogmas of Scholasticism with those of a new corpuscularian and mechanist metaphysics? Were mechanism and experimentalism, on the whole, overlapping or antagonist movements?
  2. Some experimentalists explicitly endorsed corpuscularism and mechanism. Were their arguments for these views empirical arguments, or were they the sort of a priori arguments that experimental philosophers professed to eschew?
  3. Similar questions arise for experimental philosophers’ theological commitments. To what extent did the experimentalists’ natural philosophy depend on substantive theological assumptions that, being endorsed in an a priori fashion, were incompatible with their experimentalist commitments?
B. Early modern ethics and introspection:
  1. When was the method of experimental philosophy first applied to ethics? Scholars often point to Hume’s Treatise of 1739-1740. Yet, Hume acknowledged that it was Hutcheson who began ‘to put the science of man on a new footing’ (Treatise, 6-7). The works of several other Scottish authors also deserve close scrutiny.
  2. Scholars often note that eighteenth-century philosophers endeavoured to apply the Newtonian method to ethics. However, they rarely discuss the exact nature of this alleged ‘moral Newtonianism’. Some, like Eric Schliesser, claim that professions of Newtonianism masked decidedly anti-Newtonian attitudes. What does, exactly, the Newtonianism of Hutcheson, Turnbull, Fordyce, Hume, and Reid amount to?
  3. The primary surrogate for experiments that early modern experimental moral philosophers used as the basis for identifying moral laws was ‘experimenting in one’s mind’, that is, introspection. Yet, the experimentalists’ recourse to introspection looks suspiciously similar to the sort of armchair theorizing that old and new experimentalists aim to supersede. To what extent did recourse to introspection, as opposed to more reliable experimental procedures of current-day empirical psychology, undermine early modern authors’ endeavours to ground practical philosophy on experiment and observation?
C. The viability of an empirical science of ethics:
  1. Several current-day naturalists replace introspection with the evidence provided by experimental psychology, brain science, and evolutionary biology as the primary source of ‘ethical observations’. However, they share the methodological outlook of eighteenth-century experimental philosophers, insofar as they claim that normative ethics must be based on experiments and observations and that ethical facts must be studied with the same methods of natural facts. The plausibility of this view is called into question by the recent revival of arguments for the view that we cannot study moral facts with empirical methods because they are irreducible to natural facts. Are those arguments sound?
  2. Early modern experimental philosophers liken the derivation of moral norms from observed facts to Newton’s ‘deduction [of natural laws] from the phenomena’. The latter could be spelt out as an inference to the best explanation. Yet the view that moral norms provide the best explanations of people’s actual, observable behaviour is far less plausible. Is there an asymmetry between the derivation of natural laws and that of moral norms from the relevant observable phenomena? If so, how does it affect old and new attempts to extend the explanatory models of natural science to ethics?
  3. Are the main arguments with which prominent scientists and intellectuals advocate the replacement of traditional armchair ethical reflection with an empirical science of morality sound?

We will address these questions in a series of publications and events.