Cause
Causal
arguments attempt to support causal statements - those that reduce to the claim
that A causes B.
-
cause may be particular ie. this individual thing caused, is causing, or
will cause something - or they may be general
ie. this type of thing causes this other type.
-
causes may be affirmative or negative.
We
have immediate cause, proximate cause.
Causes
are not exclusionary: different interests suggest different avenues of
prevention, or cure, and hence different causes.
Unlike
“did” and “do” causal statements, which require more proof, “could”
causal statements are established simply by getting duplicate results in
duplicate conditions.
A
true “could” causal statement
definitely rebuts a claim that something cannot be or have been done.
Most
causation results not from a single claim of immediate and proximate causes,
but from complexes of factors.
When
wishing to emphasise the complexity of a problem people speak of contributory
causes (no one thing is responsible).
Many
a perceived “difference” has turned out to be purely psychological.
Assessing
the causal arguments of others, is frequently an obligation of good
citizenship. Therefore it is important
to have explicitly in mind what good causal arguments look like, and to be
articulate at explaining the strengths and weaknesses of those sorts of causal
arguments.
Good
causal arguments are (1) congruent (they state a
connection between occurrence or phenomena), (2) always contain an exclusion
aspect, a ruling out.
-
if we connect two occurrences we have a connection but not yet a causal
connection.
correlation
- a repeated, regular connection between one phenomena and another.
-
a correlation connects one phenomenon with another.
-
correlations may be of degree.
Correlations
may be positive, or direct, or they may be inverse, or negative.
Many
correlations are coincidence. Then again
many correlations result not from the action of one variable upon another but
from that of yet another variable.
Some
correlations, though parts of a causal chain, do not count as causal because
their point in the chain is not the one at which we can exert control, or is
incidental to the point in the chain where we can exert it.
post hoc ergo propter hoc
= “after it, therefore because of it”,
an error in logic or bad causal reasoning.
A
simple causal argument can be seen as built on an “if then” premise, the causal hypothesis.
Good
causal arguments are twofold comparisons, (1) “before” and “after”, but
requires a control group[(i) a control is matched to the material being tested
in every respect except one, namely the alleged cause, (ii) a test or trial is
run, (iii) if the test material undergoes change and the control does not then
the change is attributable to the difference]
retrospective
and prospective
studies make use of natural controls.
-
retrospective studies can be valuable in defining causal issues and in
leading to breakthroughs, but they are rarely sufficient to settle causal
issues.
-
even second-best attempts at controls are better than no attempt.
The
term
“control” denotes not only the standard against which a supposed causal
change is measured but also the whole process of monitoring and regulating the
many details, which could affect the result.
Placebo
effect - “effects”
tend to occur for no other reason than that subjects expect them to occur.
Test
should be done blind ie. the subjects not knowing which stimulus, which batch,
they are sampling.
-
the test should be repeated (replicated).
Avoid
a possible order effect, half the subjects should be given the test
material first and half given to the control first.
“fatigue”
effect - senses become dull upon successive simulation.
crossover
- test and control are reversed in a latter trial.
Groups
which are to be compared must be comparable.
A
result is said to be causally significant when the probability of its having
occurred by chance falls below a certain level.
Significance
will be higher the greater the difference between control and test groups. the
greater the number of trials, the greater the number of individuals and the
less the inherent variability in the material.
No comments:
Post a Comment