Minds and Computers : An Introduction to the Philosophy of Artificial Intelligence

direction. She asserts that physical states give rise to mental states, but
denies the problematic converse.
The epiphenomenalist does not run afoul of the problem of inter-
action as she does maintain the causal closure of the physical universe.
According to epiphenomenalism, every physical event is wholly and
solely accounted for by antecedent physical events. In other words,
every physical e
ffect has a physical cause. As well as having physical
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e
ffects, though, some physical states are held to also give rise to
mental states.
The epiphenomenalist picture, then, is one of a chain of physical
causation containing some physical states which also give rise to
mental states. These mental states are held to be causally ine
fficacious
– they don’t do anything. Mental states, on this view, are mere epiphe-
nomena of physical states. They are accounted for by physical states but
they themselves cause neither physical states nor further mental states.
It is likely to be less than clear to you why one might want to main-
tain a theory which sees mental states as ontologically distinct from
their associated physical states, yet causally ine
fficacious in both the
physical and the mental realms. This is likely to become a lot clearer
later in this volume when we discuss the privileged first-person experi-
ence of having or being in a mental state. For now, it is only important
that you understand the mechanics of the theory and the way in
which it di
ffers from the other kinds of ontological dualism we have
examined.
2.6 ANOMALOUS MONISM
A final theory we should at least mention before concluding this
chapter is anomalous monism, otherwise known as double aspect
theory or, simply, property dualism.
Anomalous monism is not, strictly speaking, a dualist theory in the
sense of each of the other theories in this chapter, since the anom-
alous monist is not a substance dualist. The dualism they advance –
such as it is – is a dualism of properties, not substances.
According to the anomalous monist, there is no non-physical sub-
stance. There are however, they contend, irreducibly non-physical
properties of physical substance. In other words, certain physical
states have a double aspect – they have both ordinary physical prop-
erties and certain non-physical properties which are not reducible to
(explicable in terms of) their physical properties.
Understanding in detail the metaphysics of irreducibly non-
physical properties requires a modicum of philosophical sophistica-
tion. The interested reader is encouraged to follow the suggestions
for further reading to direct their research.
Again, it is likely to be less than clear why one might be inclined to
maintain anomalous monism. The same material which will hope-
fully shed some light on the intuitions underlying epiphenomenalism
should also go some way towards making clear the motivations
behind anomalous monism.
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C H A P T E R 3
BEHAVIOURISM
The next theory of mind we’re going to examine is philosophical
behaviourism. Before we do so, however, it will serve us to take a short
detour into the history of psychology.
One good reason for taking this detour is that the prevailing intel-
lectual climate in which philosophical behaviourism was first formu-
lated was one in which empirical psychology was still finding its feet
as a ‘science of mind’. Psychologists and philosophers were still very
much trying to work out what psychology was in the business of
doing and there was a concerted e
ffort to formulate a robust philo-
sophical theory of mind in which mentality was amenable to empir-
ical investigation. Understanding the contemporaneous presence of
psychology on the intellectual world stage gives us significant insight
into the motivations of philosophical behaviourists.
Another good reason for the detour is that the term ‘behaviourism’
means something rather di
fferent in the mouths of psychologists than
it does in the mouths of philosophers. Since there is scope for confu-
sion here, it pays to be rigorous in disambiguating the two senses of
‘behaviourism’.
Psychology is by far the youngest fully-fledged academic discipline,
as it was the most recent of the disciplines to split from philosophy. It
was only in the early twentieth century that psychology broke away
and became an academic speciality in its own right. As such, we
needn’t go far back in history to trace the genesis and nascency of
psychology. The story begins in Germany in the nineteenth century.
3.1 EARLY EMPIRICAL PSYCHOLOGY
The treatment of the history of psychology here will be rather
cursory. For our purposes, it serves to identify a few key figures and
seminal contributions which led to the birth of psychology as a dis-
tinct academic speciality. Roughly and broadly speaking, we can
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divide the infancy and early childhood of psychology into three
stages, distinguished by the methodologies employed by the disci-
pline’s progenitors.
3.2 PHYSIOLOGICAL PSYCHOLOGY
Although we will reserve the title of ‘founder of psychology’ for
another, Gustav Fechner (1801–87) must be credited with the incep-
tion of the empirical tradition in psychology and the delivery of the
first quantitative psychological law.
Before Fechner, there was a long-standing tradition of empirical
physiology, but mentality had only ever been investigated a priori,
never experimentally. Fechner was trained initially as a physiologist,
before becoming Professor of Physics and, later, Professor of
Philosophy at Leipzig.
Fechner discovered that the way we perceive the intensity of
sensory input is logarithmically proportional to the absolute magni-
tude of the stimulus. For instance, the way we perceive loudness is log-
arithmically proportional to the absolute magnitude of the sound
waves. You may have noticed that the decibel scale which quantifies
the loudness of sound is a logarithmic scale. Fechner’s result has
proven to be a robustly manifest quantitative relationship across the
sensory modalities.
We shouldn’t underestimate the importance of this result in
demonstrating the possibility of, and originating a psychophysical
methodology for, an empirical science of the mind. For the first time
in intellectual history, we see the identification of an observable and
measurable relationship between physical phenomena and mental
phenomena.
The other major figure in the physiological tradition of early psy-
chology is Hermann Helmholtz (1821–94). Like Fechner, Helmholtz
had wide-ranging academic interests. He was initially educated in phi-
losophy and philology at Potsdam and in medicine in Berlin. During
his academic career he held chairs in physiology at Königsberg,
anatomy and physiology at Bonn, physiology at Heidelberg and
physics at Berlin. He also presided over the development of a new
Institute for Physiology at Heidelberg and a new Institute for Physics
at Berlin.
As well as making significant contributions to physiological optics –
including the invention of the ophthalmoscope and the ophthal-
mometer – and delivering important unifying results in theoretical
physics, Helmholtz experimented on nerve conduction. His early
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experiments aimed to measure the time it took for neural impulses to
travel in animal limbs. He later extended this research to human sub-
jects and, in doing so, introduced a versatile experimental technique
that is still widely employed in psychology today – the measurement of