MORE EFFECTIVE REASONING II: BETTER LINKS 81always offer enough support for your audience to be convinced that the conclusion
of your argument is acceptable or that the explanation of it is complete. Strength
of support is, like relevance, very dependent upon the context in which we are
reasoning, and we can never be certain that we have given enough support for our
conclusions. On the other hand, if we do think about this context, then we can
greatly improve the chances that we will be effective.
The first such context issue concerns the burden of proof. The following
example is drawn from a legal situation. In a court case, the two opposing parties
do not come to court each with an equal task. In a criminal trial, for example, the
prosecution has the burden of proof. If it fails to establish the guilt of the
defendant, then the defendant goes free; the defence does not have to prove
innocence, but must merely defeat the prosecution's attempts to prove guilt. There
are two common measures of the burden of proof in the law. In criminal cases, the
prosecution must prove beyond reasonable doubt that the defendant is guilty. In civil
cases, a less onerous burden is carried by the plaintiff (the one who initiates the
action). The plaintiff must prove, on the balance of probabilities, that they are right;
the respondent's task is to establish a greater probability that their side of the
argument is correct.
It is rare, outside legal and quasi-legal contexts, for the burden of proof on one
side of an argument to be recognised formally. Yet, the implicit idea behind it is
found in all reasoning. One person has a more demanding job of proving a point
and, if they fail, then an alternative position remains the preferred one. One person
must provide more evidence, must positively show their conclusion to be true.
Usually existing conclusions require less evidence or, perhaps, will be taken to be
true unless clearly shown otherwise. Obviously, those who have the burden of proof
in an argumentative situation will need stronger, more compelling support for their
conclusion than their opponents. The problem, however, is to determine where this
burden lies.
As with all these contextually based judgments, it is impossible to provide some
ready formula by which we can always ascertain the burden of proof—who has it
and how onerous it is. Each situation will be different. However, as a general rule,
we must (when arguing or explaining) consider the established true claims that
conflict with our proposed reasoning. For example:
Historians in twentieth-century Australia had, up until the 1970s, a
well-established position on Aboriginal responses to white invasion:
Aboriginal people, it was claimed and accepted, did little to resist the
encroachment of Europeans' settlement. Both experts and the commu-
nity agreed; this view was found in numerous books and articles. In fact,
few historians even bothered to explore the issue, since they were sure
they had the correct answer to the question 'What was the Aborigines'
response?'. Then, from about 1972 onwards, historians began to look
again at the evidence and come to startling new conclusions. But, as
Henry Reynolds, a leading exponent of this historical revision, has
noted, he and like-minded historians had to amass significant amounts