can even be conceived at the low end of the alcohol-consumption continuum. That is, a
subject prohibited from drinking any alcohol might argue that this for him unnatural and
unaccustomed regimen changed his personality, undermined his career, and ruined his
marriage, and with this claim in hand, could readily find a lawyer willing to help him
sue for damages.
And if such an experiment had ever been conducted, it would
be invalid
Manipulating long-term alcohol consumption in an experiment would fail to meet the
double-blind requirement. And although we are certain that an experiment manipulating
alcohol consumption over an extended period has never been conducted, even if it were
conducted, it would nevertheless contain inescapable flaws which would stand in the way
of permitting cause-effect conclusions. For example, you may be aware that the best
experiments are ones that are "double-blind." A "blind" experiment is one in which the
subjects do not know what experimental condition they are in - they might not know, for
example, whether the pill they are swallowing contains a curative drug, or only a
placebo. In our alcohol experiment, they would not know whether the liquid they were
drinking was wine, or only some wine-colored and wine-flavored water that had been
sealed in wine bottles. Already, we see the impossibility of our wine experiment being
even so much as blind. Just about every subject in our wine experiment would
immediately realize what it was that he was drinking. Tinted water is clearly
distinguishable by its appearance and taste and effect from wine. A blind wine
experiment, then, is an utter impossibility. Most subjects would be able to quickly
infer approximately what experimental condition they had been placed into.
A "double-blind" experiment would be one in which neither the subject nor the
experimenter knew what experimental condition any particular subject was in. For
example, the experimenter hands the subject a capsule, but does not himself know until
the experiment is over whether that capsule contains a curative drug or only a placebo.
In our alcohol experiment, a double-blind experiment would involve the experimenter
monitoring the life and health of each subject, but only after the experiment was over
opening up the sealed envelope to find out how much alcohol that subject had been
consuming over the past 30 years. Utterly impossible as well.
The reason that the double-blind requirement is essential is that without it,
confounding factors appear that might be responsible for any observed longevity
effects. For example, subjects aware that they are in a large-alcohol-consumption group
would also tend to realize that such alcohol consumption might harm them, and so they
might attempt to compensate by taking vitamin pills, not smoking, upgrading their diets,
exercising, and so on. Or, they might start eating fats prior to drinking alcohol, in
order to coat their stomachs and slow the absorption of the alcohol. They might do a
large number of things. What is important is that the knowledge of one's experimental
treatment can lead to one or more changes in behavior, and that it is these unintended
changes, and not the wine consumption itself, that could affect longevity, either in one
direction or the other.
Or, here is a particularly plausible confounding that might appear. Imagine that the
experiment attempts to control wine drinking, and no more than that, and that subjects
do faithfully follow the wine regimen that is imposed on them. Nevertheless, the less
wine that they were allowed to drink, the more beer and hard alcohol they would probably
end up drinking, but which would make the initially equal groups unequal on beer and
hard-alcohol consumption. And so then it would be impossible to tell if differences in
longevity should be attributed to differences in wine consumption, or to differences in