I've been doing a bit of reading about the formation of the moon, and I've found multiple references (1, 2, 3) to something called Taylor's axiom, stated in link (3) above as:

The best models for lunar origin are the testable ones.

A few related questions:

  1. Who came up with it? If it was, in fact, someone named Taylor (which it need not be), which Taylor?
  2. Is there a paper/talk/etc that contains a definitive form of Taylor's axiom?
  3. I think we can all agree that testable models are the best ones. Why, then, did Taylor's axiom even need to be stated? e.g. was there a time when when untestable theories of lunar formation were in vogue or something?

2 Answers 2


Just a shot in the dark, as the journal in which this article has been published has no online presence and is not available in paper form in my institution, but it might refer to an article by a Richard L. S. Taylor from 1990 called 'The Damocles Hypothesis', published in the journal "Space" (journal edited by the University of London it seems).

Follows the abstract of that article:

Consideration is given to the use of data from the Apollo missions to study theories of the origin and geological evolution of the moon. Theories of lunar origin are examined, including origin by fission, binary accretion origin, the capture hypothesis, and the giant impact model. Apollo data related to each of these theories is summarized, showing that the giant impact model is the most probable theory for the origin of the moon. The giant impact model is outlined, focusing on the collision between the earth and a large body called Damocles.


The axiom and corollary appear to have originated at a conference held in 1984 and are named after Stuart Ross Taylor, at the time affiliated with the Research School of Earth Sciences, Australian National University, Canberra.

Stuart Ross Taylor, "The Origin of the Moon: Geochemical Considerations", In W.R. Hartmann, R.J. William, and G. J Taylor (eds.), Proceedings of the Conference Origin of the moon, Kona, HI, October 13-16, 1984. Houston: Lunar and Planetary Institute 1986, pp. 125-143 (scan online). At the end of the paper one finds:

Hypotheses in science should be testable. A test to distinguish between the two viable hypotheses of lunar origin, large impactor and double planet, can be made in principle by dating the volatile depletion event.

This statement may have triggered some discussion on the issue of testability, because a prefatory page in the conference record that I found described in Robert Malcuit, Geoforming Mars: How could nature have made Mars more like Earth?, Springer 2021, p. 142, supposedly reads as follows:

The Page Before the PREFACE (Unlabeled Page VI) Has a Few Interesting Comments by at Least Two of the Participants (in Approximately the Same Format as the Page in the Book)

The best models for lunar origin are the testable ones.

The testable models for lunar origin are wrong. — S. Ross Taylor paraphrased by Sean Solomon, at the Conference on the Origin of the Moon, Kona, 1984.

So far I have been unable to find a scan of the relevant page of the conference proceedings online to confirm this description, however I found a blog post "The Genesis of the Moon" that provides matching information. Google provides merely snippet views (1, 2, 3) of page VI, just enough to confirm that this page holds the relevant information.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.