behave. Additionally, it harmonises with how the major schools of behavioural
science spread across a spectrum locating deterministic theories at one end
and voluntaristic theories at the other. This middle view is adopted here, and is
labelled qualified determinism. People generally choose how to behave, but
often make their choice because of strong motivation or other forces. To an
extent this conclusion is supported by the reasons just stated. To an extent it is
also an assumption.
Science
Economists set themselves too easy, too useless a task if in tempestuous
seasons they can only tell us that when the storm is long past that the ocean
is flat again.
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Introduction
When legislators and judges make and interpret law consciously or
unconsciously they rely on causal or behavioural laws. Behavioural laws
should identify the effects that statutes and their interpretation might cause or
can cause. The point is that identifying these effects is fundamental for
applying the net benefit rule, which is the fundamental rule for making and
interpreting law. Ideally, these causal laws are properly supported by scientific
inquiry. In practice this is not always the case for two reasons. First, while
behavioural science has reached the point where it can explain much, it still
cannot provide explanations for a considerable amount of behaviour by
pointing to a
causal law that drives the behaviour. Second, legislators and
judges are generally not trained in behavioural science so that even if there is a
relevant behavioural law, they may not know of its existence.
Using Science
Introduction
Science is based on proper method. Laws that explain causation in human
behaviour are most reliable when they have been derived from using a
scientific method of investigation and proof. For this reason to understand
legal reasoning it is important to have some knowledge of scientific method.
Scientific method, however, is a complex topic, incorporating logical
reasoning, statistics and probability. For this reason it is not possible to give
anything more than a brief account. This will consist of looking at three of the
main methods used and explaining the reasoning processes involved.
Hypothetico Deductive Method
Assume that medical scientists have done some study on Disease X. This
study strongly suggests, but without actually proving it, that a deficiency in the
body of Substance Y is the continuing cause of Disease X. This means that if
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JM Keynes (1923) A Tract on Monetary Reform
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