String theory and post-empiricism

[Jim__]

An essay by Peter Woit, a theoretical physicist, on the scientific status of string theory.

An excerpt from the essay:

...

Last month’s conference in Princeton included two remarkable talks by prominent physicists, both of whom invoked philosophy in a manner unprecedented for this kind of scientific gathering. On the first day, Paul Steinhardt attacked the current practice of inflationary cosmology as able to accommodate any experimental result, so, on philosophical grounds, no longer science [2]. He included a video clip of Richard Feynman characterizing this sort of thing as “cargo cult physics.” On the final day, David Gross interpreted Steinhardt’s talk as implicitly applying to string theory, then went on to invoke a philosopher’s new book to defend string theory, arguing that string theorists needed to read the book in order to learn how to defend what they do as science [3].

The book in question was Richard Dawid’s String Theory and the Scientific Method [4], which comes with blurbs from Gross and string theorist John Schwarz on the cover. Dawid is a physicist turned philosopher, and he makes the claim that string theory shows that conventional ideas about theory confirmation need to be revised to accommodate new scientific practice and the increasing significance of “non-empirical theory confirmation.” The issues of this kind raised by string theory are complex, so much so that I once decided to write a whole book on the topic [5]. A decade later I think the arguments of that book still hold up well, with its point of view about string theory now much more widespread among working physicists. One thing I wasn’t aware of back then was the literature in philosophy of science about “progressive” vs. “degenerating” research programs, which now seems to me quite relevant to the question of how to think about evaluating string theory.

I’ve written a bit about the Dawid book and earlier work of his [6], although as for any serious book there’s of course much more to say, even if I lack the time or energy for it. Recently an interview with Dawid appeared, entitled “String theory and post-empiricism,” which summarizes his views and makes some claims about string theory critics which deserve a response, so that will be the topic here. In the interview he says:

I think that those critics make two mistakes. First, they implicitly presume that there is an unchanging conception of theory confirmation that can serve as an eternal criterion for sound scientific reasoning. If this were the case, showing that a certain group violates that criterion would per se refute that group’s line of reasoning. But we have no god-given principles of theory confirmation. The principles we have are themselves a product of the scientific process. They vary from context to context and they change with time based on scientific progress. This means that, in order to criticize a strategy of theory assessment, it’s not enough to point out that the strategy doesn’t agree with a particular more traditional notion.
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more ...

Richard Dawid, a philosopher with a doctorate in physics, who takes an opposing view, is interviewed here.

[BillZBubb]

1. I thought this was a strange claim:

"I think that those critics make two mistakes. First, they implicitly presume that there is an unchanging conception of theory confirmation that can serve as an eternal criterion for sound scientific reasoning. If this were the case, showing that a certain group violates that criterion would per se refute that group’s line of reasoning."

Showing a line of reasoning doesn't conform to current requirements of scientific reasoning does not refute that line of reasoning at all. It simply indicates the line of reasoning has an extremely heavy burden to convince other scientists of its truth. In other words it states the line of reasoning is incomplete, not necessarily wrong.

I do think it is a hard sell to proclaim a theory the true picture of nature when you can produce no empirical evidence beyond the fact that the equations match the data.

String theory, for example, requires several extra dimensions to provide accurate results. If strings are real, the dimensions must be there. If not, the extra dimension are just "fudge factors" used to create a way to calculate the correct results but with no basis in nature. We won't know if String Theory is true or not until someone can crack the extra dimension puzzle.

[FiveGoodMen]

2. So ... faith-based science.

[d_r]

3. is empricism still supposed to be dead?

I remember hearing of its death in 1992 or so, but the zombie of empiricism has been raising hell with education policy ever since.

[MisterP]

4. the real problem is when the empirical and theoretical are divided--as though we only

need our right or left legs for walking and not both!
but like I always say, splitting the two apart turns science into some kind of bad boyfriend, who's always right ESPECIALLY when he reverses his opinion

[d_r]

5. that's a really good point

and example