anthropic-principle.com

[Judith Rosen <***>]

This was the most coherent description I found on the subject Howard raised. Many of the people using the term on the internet are what I would evaluate as "cranks" but this one (www.anthropic-principle.com)  is talking about very serious issues that certainly were involved in my father's reassessment of the history of science and describe much of what he was looking for as he did his analysis. To my knowledge, Robert Rosen never used the term "Anthropic Principle" though, and that was probably because he was doing this kind of thing from childhood whereas it got it's name around 1974. He may have dubbed these principles (as described below) "Kantian". I call them "basic common sense".

 

Judith Rosen

 

 

 

anthropic-principle.com

...Introduction....

OBSERVATION SELECTION EFFECTS

How big is the smallest fish in the pond? You catch one hundred fishes, all of which are greater than six inches. Does this evidence support the hypothesis that no fish in the pond is much less than six inches long? Not if your net can?t catch smaller fish.

Knowledge about limitations of your data collection process affects what inferences you can draw from the data. In the case of the fish-size-estimation problem, a selection effect?the net?s sampling only the big fish?vitiates any attempt to extrapolate from the catch to the population remaining in the water. Had your net instead sampled randomly from all the fish, then finding a hundred fishes all greater than a foot would have been good evidence that few if any of the fish remaining are much smaller.

In 1936, the Literary Digest conducted a poll to forecast the result of the upcoming presidential election. They predicted that Alf Landon, the Republican candidate, would win by a large margin. In the actual election, the incumbent Franklin D. Roosevelt won a landslide victory. The Literary Digest had harvested the addresses of the people they sent the survey to mainly from telephone books and motor vehicle registries, thereby introducing an important selection effect. The poor of the depression era, a group where support for Roosevelt was especially strong, often did not have a phone or a car. A methodologically more sophisticated forecast would either have used a more representative polling group or at least factored in known and suspected selection effects.

 

 In these three examples, a selection effect is introduced by the fact that the instrument you use to collect data (a fishing net, a mail survey, preserved trading records) samples only from a proper subset of the target domain. Analogously, there are selection effects that arise not from the limitations of some measuring device but from the fact that all observations require the existence of an appropriately positioned observer. Our data is filtered not only by limitations in our instrumentation but also by the precondition that somebody be there to ?have? the data yielded by the instruments (and to build the instruments in the first place). The biases that occur due to that precondition?we shall call them observation selection effects?are the subject matter of this book.

Anthropic reasoning, which seeks to detect, diagnose, and cure such biases, is a philosophical goldmine. Few fields are so rich in empirical implications, touch on so many important scientific questions, pose such intricate paradoxes, and contain such generous quantities of conceptual and methodological confusion that need to be sorted out. Working in this area is a lot of intellectual fun.

Let?s look at an example where an observation selection effect is involved: We find that intelligent life evolved on Earth. Naively, one might think that this piece of evidence suggests that life is likely to evolve on most Earth-like planets. But that would be to overlook an observation selection effect. For no matter how small the proportion of all Earth-like planets that evolve intelligent life, we will find ourselves on a planet that did (or we will trace our origin to a planet where intelligent life evolved, in case we are born in a space colony). Our data point?that intelligent life arose on our planet?is predicted equally well by the hypothesis that intelligent life is very improbable even on Earth-like planets as by the hypothesis that intelligent life is highly probable on Earth-like planets. This datum therefore does not distinguish between the two hypotheses, provided that on both hypotheses intelligent life would have evolved somewhere. (On the other hand, if the ?intelligent-life-is-improbable? hypothesis asserted that intelligent life was so improbable that is was unlikely to have evolved anywhere in the whole cosmos, then the evidence that intelligent life evolved on Earth would count against it. For this hypothesis would not have predicted our observation. In fact, it would have predicted that there would have been no observations at all.)

The term ?anthropic principle?, which has been used to label a widerange of things only some of which bear a connection to observation selection effects, is less than three decades old. There are, however, precursors from much earlier dates. For example, in Hume?s Dialogues Concerning Natural Religion, one can find early expressions of some ideas of anthropic selection effects. Some of the core elements of Kant?s philosophy about how the world of our experience is conditioned on the forms of our sensory and intellectual faculties are not completely unrelated to modern ideas about observation selection effects as important methodological considerations in theory-evaluation, although there are also fundamental differences. In Ludwig Boltzmann?s attempt to give a thermodynamic account of time?s arrow (Boltzmann 1897), we find for perhaps the first time a scientific argument that makes clever use of observation selection effects. We shall discuss Boltzmann?s argument in one of the sections of chapter 4, and show why it fails. A more successful invocation of observation selection effects was made by R. H. Dicke (Dicke 1961), who used it to explain away some of the ?large-number coincidences?, rough order-of-magnitude matches between some seemingly unrelated physical constants and cosmic parameters, that had previously misled such eminent physicists as Eddington and Dirac into a futile quest for an explanation involving bold physical postulations.

The modern era of anthropic reasoning dawned quite recently, with a series of papers by Brandon Carter, another cosmologist. Carter coined the term ?anthropic principle? in 1974, clearly intending it to convey some useful guidance about how to reason under observation selection effects. We shall later look at some examples of how he applied his methodological ideas to both physics and biology. While Carter himself evidently knew how to apply his principle to get interesting results, he unfortunately did not manage to explain it well enough to enable all his followers to do the same.

The term ?anthropic? is a misnomer. Reasoning about observation selection effects has nothing in particular to do with homo sapiens, but rather with observers in general. Carter regrets not having chosen a better name, which would no doubt have prevented much of the confusion that has plagued the field. When John Barrow and Frank Tipler introduced anthropic reasoning to a wider audience in 1986 with the publication of The Anthropic Cosmological Principle, they compounded the terminological disorder by minting several new ?anthropic principles?, some of which have little if any connection to observation selection effects.

A total of over thirty anthropic principles have been formulated and many of them have been defined several times over?in nonequivalent ways?by different authors, and sometimes even by the same authors on different occasions. Not surprisingly, the result has been some pretty wild confusion concerning what the whole thing is about. Some reject anthropic reasoning out of hand as representing an obsolete and irrational form of anthropocentrism. Some hold that anthropic inferences rest on elementary mistakes in probability calculus. Some maintain that at least some of the anthropic principles are tautological and therefore indisputable. Tautological principles have been dismissed by some as empty and thus of no interest or ability to do explanatory work. Others have insisted that like some results in mathematics, though analytically true, anthropic principles can nonetheless be interesting and illuminating. Others still purport to derive empirical predictions from these same principles and regard them as testable hypotheses.We shall want to distance ourselves from most of these would-be codifications of the anthropic organon. Some reassurance comes from the metalevel consideration that anthropic reasoning is used and taken seriously by a range of leading physicists. One would not expect this bunch of hardheaded scientists to be just blowing so much hot air. And we shall see that once one has carefully removed extraneous principles, misconceptions, fallacies and misdescriptions, one does indeed find a precious core of methodological insights

The field of observational selection has begun to experience rapid growth in recent years. Many of the of the most important results date back only about a decade or less. Philosophers and scientists (especially cosmologists) deserve about equal parts of the credit for the ideas that have already been developed and which this book can now use as building blocks.