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

any kind of physical event. So my thinking of ice cream must be a non-
physical event – mentality must be a non-physical phenomenon, in
which case we are committed to substance dualism at the least.
The argument from introspective appearance, as given in the previ-
ous paragraph, su
ffers a rather tenuous connection between its
premises – which are concerned with the way things seem to us – and
its conclusion, which maintains that the way things are is in accord
with the way things seem. The obvious reply, then, to the argument
from introspective appearance is to point out that there is no neces-
sary connection between the way things appear to us and the way
things actually are. In fact, we are very often deceived by the way
things seem: a warm breeze doesn’t seem at all like the kinetic energy
of millions of molecules, nor does electricity seem at all like a flow of
electrons.
The way things seem, however, in no way establishes a distinction
between a warm breeze and the kinetic energy of millions of mole-
cules on the one hand, or between electricity and a flow of electrons
on the other. Similarly, the way our minds seem to us cannot be relied
upon to establish the non-physicality of mentality.
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The fallibility of appearances certainly does not entail that men-
tality cannot be non-physical. It merely shows that the argument from
introspective appearance fails as an argument in favour of the non-
physicality of mentality as it fails to establish the required necessary
connection between the truth of its premises and the truth of its con-
clusion.
2 . 3 . 3 T H E A RG U M E N T F R O M E S S E N T I A L P R O P E RT I E S
The argument from introspective appearance appealed to the fact that
minds have certain essential properties which ordinary physical
objects lack, and vice versa. For one thing, minds have this essential
capacity for direct introspection and reflective awareness that ordi-
nary physical objects do not have. But minds and physical objects also
di
ffer in other essential ways.
Ordinary physical objects are essentially publicly accessible
(anyone can observe a chair) whereas minds are not (only I can
directly observe my mind). Ordinary physical objects are also essen-
tially extended in space – they have mass, shape, location and other
spatial properties. Minds, on the other hand, are essentially thinking
things: they don’t, merely by virtue of being minds, have spatial
properties in the way that a chair, merely by virtue of being a chair,
has spatial properties. The only properties minds have merely by
virtue of being minds are those pertaining to capacities to think. It is
not an essential property of minds that they are extended in space in
the way that it is an essential property of ordinary physical objects,
such as chairs, that they be spatially extended.
Given this radical divergence in essential properties between minds
and ordinary physical objects, there must, then, be a distinction in kind
– minds must be a di
fferent kind of thing to physical objects. They
must, therefore, be non-physical entities.
While the argument from essential properties we have just rehearsed
seems initially compelling, a little thought serves to dispel its force.
There is much we could say about the metaphysics of essential proper-
ties which the argument trades on. For present purposes, however, it
su
ffices to recognise that a distinction in kind is not tantamount to a
metaphysically substantive distinction.
In other words, we can adopt the same strategy we employed in
defusing the argument from introspective awareness – we concede the
truth of the premises but point out that this does not establish a nec-
essary connection to the truth of the conclusion. It is a given that
minds are quite unlike anything else we know of in the universe. This
does not, however, entail that minds are made of different stuff to
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  

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everything else in the universe – i.e. that minds are composed of non-