This is a section of a book I’m working on about law, neuroscience, and theology, drawn from my Ph.D. dissertation.
As discussed in Chapter 1, neurolaw is one manifestation of the “new moral science” critiqued by James Davidson Hunter’s and Paul Nedelisky’s in their excellent book Science and the Good: The Tragic Quest for the Foundations of Morality.[1] One of Hunter’s and Nedelisky’s central claims is that the new moral science fails because it violates the “is-ought” rule. According to Hunter and Nedelisky, the facts of human evolution and neurochemistry do not entail ethical imperatives because they are merely facts about what is. The are several reasons why this is the wrong line of critique, even though the critique is important.
First, Hunter and Nedelisky do not really grapple with how
neuroscientific reductionists handle the “is-ought” problem. Second, Hunter and Nedelisky overlook the “naturalistic
fallacy,” which is related to but in this case more powerful than the
“is-ought” distinction. Third, and most
importantly, Hunter and Nedelisky do not address the central question of
metaphysics.
A good conversation partner here is Patricia Churchland. In her book Braintrust: What Neuroscience Tells Us About Morality, Churchland notes that Hume’s “is-ought” rule is a narrow claim that refers to deductive logic.[2] Churchland grants that an “ought” statement cannot be derived from an “is” statement as a matter of formal logic. She argues, however, that “ought” statements can be inferred from “is” statements, “drawing on knowledge, perception, emotions, and understanding, and balancing considerations against each other.”[3] As Churchland notes, “I ought to go to the dentist” is a valid inference from the fact that “I have a horrendous toothache.”[4] Similarly, Churchland suggests, more complex social practices, including moral behavior, usually develop through inferences from various facts rather than from cold deductive logic.[5] Given Churchland’s understanding of what an “ought” can comprise, she escapes the “is-ought” rule.
The understanding of what an “ought” can comprise, however,
is the rub. Churchland’s description of
how most people navigate moral issues certainly is correct, and in fact is
consistent with millennia of reflection on virtue ethics: ethical frameworks and moral choices are
lived out in the complexity of the real world, not only in the sterile chamber
of deductive logic.
Because of her commitment to naturalism, Churchland cannot
refer the “ought” to higher purpose or end.
Instead, she refers generally to human wellbeing and suggests that some
kind of consequentialism is the best basis for legal rules that support human
wellbeing.[6] This seems to catch
Churchland in a problem related to the “is-ought” rule – the naturalistic
fallacy. As G.E. Moore first argued,
human wellbeing, defined as health, pleasure, or any other property natural to
humans, cannot define the “good.”[7] As Moore noted, when people say “Pleasure is
good, we cannot believe that they merely mean Pleasure is pleasure and nothing
more than that.”[8]
Churchland thinks Moore constructed a “mystical moat around
moral behavior.”[9] Her response to the naturalistic fallacy is
that a scientific term can include more than one aspect of meaning. She suggests, “consider these scientifically
demonstrated identifications: light (A) is electromagnetic radiation (B), or
temperature (A) is mean molecular kinetic energy (B). Here, the A and B terms are not synonymous,
but the property measured one way was found to be the same as the property
measured another way.”[10] As another more prosaic example, she suggest,
“Suppose I discover that my neighbor Bill Smith (A) is the head of the CIA (B):
are the expressions ‘my neighbor Bill Smith’ and ‘the head of the CIA
synonymous?’ Of course not.”[11]
Churchland is of course correct that a term can include more
than one aspect of meaning, but that is not what her examples demonstrate, and
in any event, she completely misses Moore’s point.
Churchland’s second example is irrelevant. “Bill Smith” and “Head of the CIA” are not
categories that overlap at all except for the contingent historical fact that
at some point in time Bill Smith serves in that role. Obviously, Bill Smith cannot be reduced to
his role as Head of the CIA, nor can the role of Head of the CIA be reduced to
the individual who currently occupies it, Bill Smith. If Bill Smith ceases to serve as Head of the
CIA, he will still be Bill Smith and there will still be a Head of the CIA. If anything, this example reinforces Moore’s
arguments against reductionism. Not only
are the terms not “synonymous,” they are not even close to coextensive.
Churchland’s example of light and electromagnetic raditaion is
no more availing. First, “radiation” is,
in fact, a synonym for “light.”[12] In at least one range of meaning –
particularly the range of meaning employed by the natural sciences –
“electromagnetic radiation” does mean “light” and “light” does mean
“electromagnetic radiation,” without remainder.
So, in the scientific domain that is Churchland’s immediate concern,
this example belies her point.
“Light,” of course, carries a much broader semantic range of
meaning than this narrow scientific one.
To say “you light up my life,” for example, has nothing to do with
electromagnetic radiation. Churchland
might respond that the experience of having one’s life lit up by a lover can be
described in the entirely material terms of hormones and neurochemistry. But this response only begs the question
whether a person’s subjective conscious experience can be reduced to such
material terms. And, in any event, “light”
now signifies something very different than “electromagnetic radiation.”
The example of “temperature” and “mean molecular kinetic
energy,” which invokes the Boltzmann constant, is more interesting. While it is true that the average kinetic
energy of molecules in a gas is proportional to temperature, mean molecular
kinetic energy is not a precise
measure of some absolute quantity of temperature. A measurement of mean kinetic energy assumes
that every molecule in the gas acts like an independent point mass. This is important for measuring heat transfer
and entropy. It is not, however, a real measure
of the specific heat of a gas, because each molecule has some degree of freedom
in its rotation and vibration and does not act like an independent point mass. Moreover, kinetic theory only applies to
gases, and even for gases, is only one way of thinking about temperature. And things become even more interesting when
“quantum thermodynamics” enters the picture, which raises major unresolved questions
about the relationship between the classical laws of thermodynamics and the
thermodynamics of systems at the quantum level.[13]
Even if Churchland wants to suggest something like “mean molecular energy : temperature :: (individual brain
chemistry + social evolution) : altruism,” the analogy breaks down on
several levels. First, as discussed
above, the left side of the analogy only applies to one specific set of
conditions. Moving to the right side of
the analogy, this would mean that “altruism” can be related to “individual
brain chemistry + social evolution” only if “altruism” is used here in a unique
way in relation to a specific kind of system.
But this would once again beg the question whether this relation
describes anything about a real world or is only a specific, limited kind of
model. And even if it were otherwise a
fair model within its own limited sphere, it would leave open the question
whether, as with quantum thermodynamics, there are other levels of possible
description, perhaps even with different rules.
This, however, is a quite generous account of the
analogy. Mean molecular energy and
temperature are related to each other proportionately, which is why one can be
used to measure the other. Brain
chemistry and evolution, in contrast, are not in the same kind of proportionate
relation to altruism or any other kind of ethically significant conduct. We can’t take the mean level of serotonin in
the brains of humans in a society and come up with any predictable measure of
altruism. Brains and social structures
are too complex for correlations here, outside very broad normal distributions,
much less for inferring causation between any discrete element of brain
chemistry or social evolution and something like levels of altruism. The notion that there might be a Boltzmann
constant for moral behavior is statistically absurd.
Finally, and most importantly, “mean
molecular energy : temperature :: (individual brain chemistry + social
evolution) : altruism,” is not really the right analogy. The right analogy is “mean molecular energy :
temperature :: (individual brain chemistry + social evolution) : the goodness of altruism.” Again, the analogy breaks down here on its
own terms. Behavior described as
altruistic might be morally good, or morally bad, or morally indifferent, or
any of these things under different circumstances. Measuring the sheer instances of a behavior
is not a moral judgment. A moral
judgment entails a measure of value the leads to some kind of imperative,
prohibition, or exhortation: altruism is
good so people ought to be altruistic if they have extra and others are in need. No one says “that container of oxygen ought to obey Boltzmann’s constant or we
will judge it to be bad oxygen.” The
oxygen has no agency and Boltzmann’s constant invariably will apply in the
domain of classical physics. This means
Churchland cannot avoid the naturalistic fallacy after all.
It also hints at the deeper metaphysical questions Churchland
refuses to address. She describes the
individual components of each set — light (A) and electromagnetic radiation
(B); and temperature (A) and mean molecular kinetic energy (B) – as
“properties.” As the Stanford
Encyclopedia of Philosophy notes, however, “[q]uestions about the nature and
existence of properties are nearly as old as philosophy itself.”[14] Any discussion of “properties” invokes the
distinction between universals and particulars and other basic problems in
metaphysics and ontology.[15] Churchland cannot dismiss these enormous
metaphysical problems with a hand-wave and then discourse about supposedly
interchangeable “properties” of light and radiation. Yet this is exactly what she does, when she confidently
asserts that “[w]hat does not exist is a Platonic Heaven wherein the Moral
Truths reside – no more than there is a Platonic Heaven wherein the Physical
Truths reside.”[16] No contemporary philosopher would frame an
answer exactly as Plato did, but the question whether “properties” are real,
and whether any such realist claim can be justified absent immaterial entities,
is the same kind of question Plato asked.
[1]
James Davidson Hunter and Paul Nedelisky, Science
and the Good: The Tragic Quest for the Foundations of Morality (New Haven:
Yale University Press 2019).
[2]
Patricia Churchland, Braintrust: What
Neuroscience Tells Us Abut Morality (Princeton: Princeton University Press
2011), 6-7.
[3] Braintrust, 6.
[4] Braintrust, 7.
[5] Braintrust, 8.
[6] Brainstrust, 175-181.
[7]
G.E. Moore, Principia Ethica
(Cambridge: Cambridge University Press 1903), § 10 ¶ 3.
[8] Principia Ethica, §
11(2).
[9]
Churchland, Brantrust, 188.
[10] Braintrust, 188.
[11] Braintrust, 188.
[12] See Thesaurus.com, “light,” available at
https://www.thesaurus.com/browse/light?s=t.
[13] See Davide Castelvecchi, “Battle Between
Quantum and Thermodynamic Laws Heats Up,” Nature,
March 30, 2017, available at https://www.scientificamerican.com/article/battle-between-quantum-and-thermodynamic-laws-heats-up/;
Natalie Wolchover, “The Quantum Thermodynamics Revolution,” Quanta Magazine, May 2, 2017, available
at https://www.quantamagazine.org/the-quantum-thermodynamics-revolution-20170502/.
[14] Stanford Encyclopedia of Philosophy, “Properties,” available at https://plato.stanford.edu/entries/properties/.
[15] See Stanford Encyclopedia of Philosophy,
“Properties.”
[16] Braintrust, 181.
