It all depends what you mean by that.
But if we assume that by soul we are
referring to a kind of unchanging identity,
which is somehow connected with the body
but not of the body, not as it were, physical,
then one would be positing something
like the Christian doctrine of the soul.
Or perhaps in Indian terms, something like
the Atman, the in-dwelling presence
of the universal spirit, of Brahma.
We don't believe in that, because,
in fact we see that merely as
a philosophical elaboration of self-clinging,
of the emotional as well as the intellectual
conviction that there is something unchanging,
either in our body or in our mind,
which is like an owner of experience,
which does not change from moment to moment,
which remains what it is at all times.
It is that very clinging to self
which sets us against the world,
because as Dharmakirti says, where there is
the clinging to self, there is also the notion of other.
So it's kind of the root of our fundamental
dividedness from reality, from the world,
to cling to such a notion.
So if soul means that type of opinion
and that type of cherishing emotion
based on upon that opinion, we do not accept it.
In fact, we subject to interrogation,
subject it to interrogation by reasoning and analysis
to conclude that, to find that, there is no such entity
in any of our five aggregates: our form,
that is our body; our sensations; our perceptions;
formations, that is to say mental factors;
or even the apprehending consciousness itself.
None of them is actually permanent,
autonomous and singular, which would
be the characteristics of such a
true self if it indeed existed.
So as we cannot find it anywhere
when we look, as it were, into the totality
of what we are from moment to moment,
and what the world is, we must conclude
there is no such self.
Now, if one says, oh in that case,
Buddhism is merely a materialist philosophy
because we reject the soul: no, of course not,
because as I've said a number of times,
we do not deny the reality of consciousness,
in fact consciousness is the one thing
from which all appearaneces, the appearances of the world actually arise.
It's simply that consciousness is not a thing,
not a box, not a static entity,
but consciousness is this stream,
this process of awareness.
So to reject the soul, or the Atman,
is to reject a restricted, shrunk down
version of what we are, but it is not
to put in its place an even more shrunken version
that is to say, we're merely matter.
So we are neither theist, nor are we materialist.
There's one final point:
we do believe, of course, there is kind of
a vitality about living beings, a kind of
force about them.
It's a conditioned thing, it comes as it were along
in the process of becoming alive,
there is this kind of, we sort of could say kind of,
a life force, or vitality, and so on,
and that can be strengthened or diminished
by appropriate conditions, but it is not a self,
or anything, it is just, as it were, a faculty,
possessed temporarily by living beings.
But it is not a soul, or a self.