Distinguished Lecture Series: Patrick Haggard (UCL)
“Benjamin Libet and the Neuroscience of ‘Free Will’: Intellectual History of an Experiment”
Patrick Haggard, Institute of Cognitive Neuroscience, University College London, Reimar-Lüst Preis / Berlin School of Mind and Braoin, HU Berlin
Host: Michael Pauen, Department of Philosophy, HU Berlin
Abstract:
Humans display a capacity for autonomous actions that far outstrips the capacities of other animals, and that underpins philosophical debates about ‘free will’. However, this volitional aspect of human action has proved hard to study scientifically. Forty years ago, Benjamin Libet published an experiment that has defined the neuroscientific investigation of human volition ever since. By combining voluntary actions, subjective time estimation, and recordings of brain activity, Libet argued that voluntary actions are caused by unconscious brain activity, rather than by any conscious intention to act. This talk attempts an intellectual history of the Libet experiment, as a way of documenting, analysing and evaluating the challenges for a neuroscience of volition. The experiment, and several critiques of it, are well known – so I will summarise these only briefly. Instead, I will take an intellectual history approach. First, the experiment has important prior context within the history of 19th century scientific investigation. Libet drew on notions of subjective chronometry that originated with Helmholtz and Wundt. However, Libet appears to have been the first to apply them to volition. Next, I will consider the afterlife of the experiment, focussing particularly on its relation to modern scientific theories of consciousness, and to recent notions of free will illusionism. At the heart of the debates about the Libet experiment, and over volition more generally, lies a division between two structuring principles of central nervous system organisation. One view emphasizes hierarchical pathways for input and output (e.g., the visual pathway, or the voluntary motor pathway), while another view emphasizes the highly-interconnected neural networks of the cerebral cortex. Libet’s work emphasizes the pathway view. This is perhaps appropriate if one believes that the distinctive feature of volition is its relation to the processes that cause bodily actions, and thus to responsibility for the external consequences of those actions. In contrast, many discussions of the Libet experiment in consciousness science have focussed on how cortical networks integrate different sources of information to produce the conscious experience of intention.
