4.3 Evidence 145
hand may also be telling the truth about what
she was told, but the receptionist may not be
telling the truth about what happened. Of
course, either of the two witnesses might be
lying or mistaken. But in the second case there
are two ways in which the evidence may be
unreliable; in the first case only one.Circumstantial evidence
By ‘circumstantial evidence’ we mean a fact, or
set of facts, which may be used to support a
conclusion or verdict indirectly. The facts
themselves – the circumstances – are not in
question. What is in question is what they
signify, or permit us to infer. Wherever an
inference is needed to get to the truth, the
evidence cannot be accepted as direct, even if
it is strong.
The classic example is the ‘smoking gun’. A
detective rushes into a room after hearing a
shot. He sees a body on the floor and a man
standing holding a gun with smoke still
coming from the barrel, indicating that it has
just been fired. The natural assumption is that
the man holding the gun is the murderer. The
detective testifies at the trial, reporting exactly
what he has seen. The suspect pleads not
guilty because, he says, he too heard the shot
and rushed into the room, and picked up the
still-smoking gun from the floor where it was
lying. The facts – the gun, the smoke, the man
holding the gun, the body on the floor – are
identical. The inferences are totally opposed.
‘A likely story!’ you may say of the suspect’s
explanation. But in the absence of any other
evidence, even the smoking gun is insufficient
for a conviction. It is (merely) circumstantial.Corroboration
If, however, it were also known that the
suspect knew the dead man, that in the past
he had threatened to kill him, that he owed
the dead man money, and/or that he had
recently visited a gun shop, then his guilt
would be rather more probable. Each of these
on its own is another piece of circumstantial
evidence, but now the various itemsstrengthened. Hence the evaluation of an
argument like [1] ultimately comes down to
evaluating the evidence from which it draws
its premises. However good the reasoning may
be, if the evidence base is false, then the
argument is groundless.
Types of evidence
As stated at the start of the chapter, evidence
can take many forms. We have been looking at
one kind, namely statistical evidence.
Evidence can usefully be subdivided into two
categories: direct and indirect. Direct evidence,
as the name suggests, is first-hand, and
immediate. The most direct form of evidence
is what we experience with our own senses. If I
see something happening in front of my eyes,
that is direct evidence – for me, at least – that it
has taken place. Of course there are occasions
when we are mistaken or confused about what
we see or hear. Also we may misremember
some of what we have experienced when we
try to recall it later. But it remains true that
personal experience is the most direct contact
that we can have with the world and what
happens in it:
Testimony
‘Testimony’ means giving an account. A
witness statement is testimony. So long as it is
an account of something that the person has
witnessed or experienced at first hand, it too
counts as direct evidence. This is in contrast to
what is known as ‘hearsay evidence’. The
difference is clearly illustrated by the following
statements by two witnesses:
W1: ‘I know Janet Winters personally, and I
saw her punch the receptionist.’
W2: ‘I found the receptionist crying and she
said that Janet Winters had punched
h e r.’It is obvious why this distinction matters. So
long as W1 is telling the truth, and is not
mistaken about what she saw, then Winters
did punch the receptionist. W2 on the other