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Wednesday, July 07, 2004


LI has always been extremely skeptical of the role of thought experiments in philosophy. Or – we have been skeptical that they are experiments. They are many things – imaginary experimental designs; fantasies; myths; and arguments; We’ve been pondering our issue with them since reading a post in Crooked Timber last week. The post responded to another post, one by Brian Leiter, about what is dead and living – in other words, what is faddish and what is uncool – in philosophy. The CT person took the opportunity to sound off about the Twin Earth “thought experiment” – and we thought, hmm, we’ve wanted to say something about the bogusness of thought experiments for some time.

So we went and looked up some of the literature. Since we are going to do this over the next couple of posts – and since our emphasis is going to be, at first, on the experiment part of the thought experiment – we’d like to point to a few links.

Here’s an article, from the Winter 2003 issue of the Journal for General Philosophy
of Science
that makes some salient comments on the limits of thought experiments in philosophy and in science.

There’s a famous argument by an Einstein scholar, John D. Norton, that thought experiments are arguments. A paper in which he develops this thesis is here.

Here’s a criticism of thought experiments in moral reasoning –especially Parfit’s moral reasoning – by Jerry Goodenough here .

To understand the difference between the design of an experiment and the experiment, we’d like to instance one experiment that bears some similarities with the kind of human experiments that epistemologists and personal identity people like to make.

In the 1960s, there were several experiments on people that seemed to show that humans have a 25 hour circadian rhythm. These experiments involved plunging people into sunlight deficient environments – deep in caves and such.

In 1999, a team at Harvard, led by Howard Czeisler, went over the data from these experiments. And they went over the experiments themselves. This is from the little Harvard news story:

“The experiments suffered from a serious flaw, however. Subjects were allowed to turn on lights, even if they were tucked away in caves or windowless labs. Several years ago, Czeisler and his colleagues discovered that ordinary room light can reset the pacemaker.
To avoid the resetting effects of room light and other cues, Czeisler, professor of medicine; Duffy, research fellow in medicine; and Dijk, assistant professor of medicine; and their colleagues tightly controlled their subjects' environment. For about a month, the 24 subjects—11 young men (mean age 24) and 13 older men and women (mean age 67)—were exposed only to very low levels of light, about one tenth that of ordinary room light. To prevent the pattern of light exposure from affecting the subjects' internal clocks, lights were turned on at progressively earlier or progressively later times of the day, essentially creating 20-hour or 28-hour days.
"The point was to decouple extrinsic cues from the internal pacemaker," says Czeisler. Despite the decoupling, body temperature, cortisol, and melatonin levels cycled on an average of every 24.18 hours. And they did so consistently among all subjects, showing the circadian pacemaker is as tightly controlled in humans as in other animals.”

The moral LI draws out of this is that experimentation does not proceed without observation, except the way a drunk proceeds on an icy road on a windy 3 a.m. It is an old, Victorian moral, such as William Whewell might be happy to adumbrate – but it is nevertheless true enough to make one ask oneself: how is a thought experiment an experiment?

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