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Unpublished Paper
Neuroscientific Evidence in the Law: Fascinating Science, but to Laymen it's still Phrenology
ExpressO (2009)
  • John M McCarthy


Neuroscientific Evidence in the Law: Fascinating Science, But to Laymen It's Still Phrenology by John M. McCarthy J.D. Yale, 1977

Cognitive neuroscience is one of biology's most exciting specialties, but outside of laboratories, "neuroscience" is not "science" but something else. The article examines what it is. This bears on today's burgeoning "neuro-" applications in the law, including "neuroethics". The article argues that neuroscientific findings should be excluded today from legal contexts, because valid scientific findings do not exist concerning the complex mental performances pertinent to adjudication.

Laymen and neuroscientists embrace a theoretical paradigm that is over two centuries old: that a biological explanation of material brain tissue will completely explain the immaterial "mind".

Scientists seek to verify the theory empirically. Narrowly drawn experiments explore manageable portions of the vast phenomenon (the brain). Since the mid-1990's, this work has become robust. Earlier efforts -- from the late 1700s, through most of the 20th century -- failed, because useful experiments were infeasible, due to ignorance of biology and a dearth of data on functioning brains.

Laymen in the legal system use the paradigm differently. Questions pertinent to them involve complex mental performances -- ethical judgment, morality, personal responsibility -- but only the most rudimentary brain functions have biological explanations today. The complex ones are not explicable. Validity of "data" on them must be established by other means. Today, ostensible validity merely accumulates from successive layers of plausibility. First, proof of a rudimentary aspect is presumed to increase the likelihood that all aspects will eventually be proven. Thus, any proof augments the plausibility of the paradigm's complex predictions.

Next, confusion of neuroscientific data, which is ambiguous, with familiar medical images, which are not, bolsters the former's plausibility. Just as cardiology has a monopoly on the heart's function, so neuroscience seemingly monopolizes the mind. Finally, conventional wisdom imports cultural fictions in which mechanical contrivances generate human personalities: Star Wars robots, Terminator, Frankenstein.

Accumulating plausibilities thus construe the brain as a flesh-and-blood contrivance, whose workings "data" can illuminate, even if neuroscience has not yet achieved that result. Incentives to endow "data" with probative weight are strong among laymen whose work would be simplified by tools that dispelled the vexing inscrutability of miscreants' minds. This includes most of the legal system and bureaucratic administration.

Laymen are employing not neuroscience, but rather an amalgam of conventional wisdom and plausible non-scientific extrapolations. Such stuff is inadmissible as scientific evidence under the Federal Rules of Evidence, as interpreted by Daubert, and its progeny. These standards should exclude neuroscientific evidence in today's state of knowledge, not only from judicial proceedings, but from all other adjudication also.

  • Neuroscience,
  • neuroethics,
  • fMRI
Publication Date
February 27, 2009
Citation Information
John M McCarthy. "Neuroscientific Evidence in the Law: Fascinating Science, but to Laymen it's still Phrenology" ExpressO (2009)
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