Lecture Notes
READING: “SENSATIONS AND BRAIN PROCESSES”
TOPIC: PHILOSOPHY OF MIND
Dualism is a theory of mind that asserts that reality consists of two types of objects –
physical objects and mental objects (or minds and bodies). Although there are several
forms of dualism, the most important and popular one has been interactive dualism,
which suggests that mental objects sometimes causes changes in bodies and that bodies
sometimes causes changes in mental objects.
The most important philosophical purpose of this theory is to answer such questions as:
how is it possible that human beings behave in the really complex ways we do behave?;
how is it that human beings are conscious?; how is it that human beings are rational, and
moral, and religious, and creative? Trees and rocks do not display this sort of behavior,
and neither to animals (though they do seem to be conscious).
Dualists thus suggest that there is some part of us that is responsible for these
phenomena, because clearly the physical part of us cannot do so. Dualism, therefore, is
thought to be an explanatory theory – that is, the concept of a separately existing, nonphysical mind is thought to provide an explanation for certain phenomena in the natural
world, namely, our own behavioral and experiential capacities.
Identity theorists like J.J.C. Smart are skeptical of the above
M1  M2
solution. Identity theorists agree with dualists that human behavior,
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and the distinctive traits of human experience require explanation,
but what sort of discipline is in the best position to offer a

B1  B2
satisfactory theory that explains that stuff? Philosophers? He doesn’t think so. His bet is
that just as scientists have been the ones who have answered such difficulty questions,
who have provided solutions to mysterious events, so will they be the ones who
eventually will supply answers to questions about how human beings do what they do.
Smart suggests that perhaps the proper way of explaining human sensation (this he takes
as a classic case of a mental phenomenon – when we see red, we are conscious of red,
aware of it, we have it “in mind”, etc.) is not through causality, but through identity!
Huh?
In other words, it would be incorrect to say that the brain causes the mind to see red, or
that a brain event causes a mental event. Rather, one ought to say that the brain event IS
the mental event, or the brain process IS a mental process. So if some set of neurons fired
in your brain and you saw red, then your seeing red was nothing other than the firing of
those neurons. The difference between the dualistic causal explanation and the
reductionist’s identity theory is that causal explanations always seem to postulate two
distinct events or objects, or processes, whereas the identity theory doesn’t. In other
words, as you can see from the model above, a brain event B1 would cause a mental
event M1. Thus supposes that there are two different events. When you bowl a bowling
ball down the lane, it hits the pins and sends them flying. In this case, there is the event of
the ball rolling down the lane at a certain rate of speed with a certain momentum, and
then you have a pin flying off to the left after the impact. So there are two events here,
not one. Similarly with Smart’s example of a burglar and footprints at the scene – the
burglar caused the footprints to be there; there are two distinct things, in this case, the
burglar and the footprint that he causes. In the case of lightning, however, there is only
one thing – the transference of huge numbers of charged particles. We see a bolt of
lighting, but there are not two things going on, the bolt of lightning and the things that
cause it, rather there is merely the pattern of electron discharge. So there might be two
languages to describe what happens, the language of the everyday in which we speak of
long bolts of white light streaking across the sky, and the scientific language in which
scientists speak of massive electrical discharges.
So it will turn out, Smart suggests, that for every mental event or process, whether seeing
an apple, remembering one’s mother, forgetting a birthday, learning a new language,
falling in love, growing resentful, there will be some brain event, more or less complex,
that will be identical to that mental event. The brain event will not cause it, it will be it.
The difference can be seen by looking at other examples: water isn’t caused by the
joining of hydrogen and oxygen atoms, it IS that particular configuration of two atoms of
hydrogen and one atom of oxygen. A book isn’t caused by its pages, it is composed of
those pages. Similarly, a bolt of lightning isn’t caused by the massive discharge of
negatively charged particles, it IS that discharge. So the experience of seeing an apple
isn’t caused by the brain state Bx (where Bx represents some extraordinarily complex
brain process, involving millions of neuronal firings), it IS that brain state. There is a
difference between taking about that brain state Bx in terms of molecules and talking
about it in terms of what the apple looks like, but that difference in language does not,
says Smart, reflect a difference in objects to which the language refers. Both types of
sentences [ (a). the apple looks round and red, (b). Bx ] refer to the very same event, but
describe the event in different ways. This is similar to a bunch of photographers
discussing how the beautiful sunset seems to them, how it appears to them, and a bunch
of neuroscientists talking about the neural activity of the photographers as they are
looking at the sunset. Smart would say that there aren’t two separate events – the
experience of seeing the sunset and the brain events going on inside their heads – there is
one thing going on, described in two different ways.
Now all of this doesn’t mean that Smart thinks there is no causality involved in the life of
the mind. The problem as he sees it is that dualists see causes where they don’t exist. In
other words, they think that mental events are causally connected to brain events,
whereas he sees mind/brain events causally connected to other mind/brain events.
So, if identity theory is true, then dualism is false.
If identity theory is true, then it is false to say that changes in mental states cause changes
in brain states.
If identity theory is true, then it is false to say that changes in brain states cause changes
in mental states.
1
C
M/B
3
2
C
M/B
M/B
In the above model, event #1 is both a neurological event, made up of neurons firing, and
that event is also conscious (say, thinking of Hawaii). #1 causes event #2, which is also a
conscious brain event (say, wanting to go to Hawaii). #2 causes #3, which is a conscious
brain event (say, realizing that going to Hawaii is impossible). So the identity theorists
believes that causal connections are crucial for understanding how the mind works, but
the causal connections that s/he pays attention to are not between mental and brain events
(since they are not different events), but rather are between one conscious brain event and
another conscious brain event.
According to the dualist, there are mental events that cause brain
events, and brain events that cause mental events, and mental events
that cause other mental events, and brain events that cause other
brain events.
M1  M2


The identity theorists suspects that all this causality is smoke and
B 1  B2
mirrors. How, for example, does a non-physical event (M1), cause a
neuron to fire? Isn’t the only way for a neuron to fire for another
neuron to fire? If the only way for one neuron to fire is by being connected in the right
way to other neurons, then it is a complete mystery how M1, which is not a physical event
(says the dualist) is supposed to exert causal pressure on B1 (B1 is just some neural
configuration of the brain)?
The identity theorist says that identity theory solves this problem. How? By suggesting
that there is no causal connection between some M and B, but only between some MB
and some other MB!