Databases Reference
In-Depth Information
When an automobile driver fails to stop at a red light and there is
an accident; it can be said that the failure to stop was the accident's
cause
.
However, negating the causal factor does not mean that the effect does not
happen; sometimes effects can be
overdetermined.
For example:
An automobile that did not fail to stop at a red light can still be
involved in an accident; another car can hit it because the other car
swerved and hit it while the car was stopped.
Similarly, negating a causal description often does not work. This is often
because an effect can be overdetermined. Also, negative statements are weaker
than positive statements as the negative statements can become
overextended.
For example, it cannot be said that
¬
α
→¬
β,
for example:
Failing to stop at a red light is not a
certain
cause
of an accident
occurring; sometimes no accident at all occurs. (There may be no
other cars; the other cars brake in time; etc.)
Negative causal relationships are less sure as negative statements are easily
overextend; but often stated; for example, it is often said that:
Not walking under a ladder prevents bad luck.
Or, usually (but not always),
Stopping for a red light avoids an accident.
Some describe events in terms of
enablement
and use counterfactual implica-
tion whose negation is implicit; for example [18]:
Not picking up the ticket
enabled
him to miss the train.
There is a multiplicity of definitions of enable and not-enable and how they
might be applied. The focus of this chapter lies elsewhere.
1.3 Complexes of Elements
In causal reasoning, commonsense reasoning may recognize that a complex
collection of elements can be involved causally in a particular effect, even if
the precise elements of the complex are unknown. It may not be known what
events are in the complex; or, what constraints and laws the complex is subject
to. Sometimes, the details underlying an event are known, sometimes not. For
example:
A tra
c jam might be observed in mid-town Manhattan. A reasonable
supposition might be made that the jam was caused by a complex
collection of elements. It might be possible to conjecture what were
some of the causes; but, it is unlikely to be able to precisely know
what were the complete set of actual causes.
