Loglan 1: A Logical Language (a.k.a. L1) by James Cooke Brown is the definitive description of TLI's Loglan language, the parent language of lojban. The First Edition of L1 (1966) was the first description of the language to be widely circulated after the 1960 publication of an eponymous article about Loglan in Scientific American magazine. Brown revised the book several times, with the final revision (as of 2017), the Revised Fourth Edition, released in electronic format in 1999.
First ("Preprint") Edition (1966)
The First Edition was labeled as a "preprint" edition and received limited circulation for review. Two notable reviews were published by Hans Freudenthall in the journal Lingua (1968) and Arnold M. Zwicky in the journal Language (1969).
Among the changes to the language relative to what was described in the Scientific American article of 1960 is a requirement for quantification, eliminating the option to reference "universals and existentials by indefinite description". This decision would be reversed in 1989 with the publication of the Fourth Edition.
Second Edition (1969)
The Second Edition was released only in microfilm.
Changes to the language relative to the previous version include a systematic distinction between the use of "afterthought" and "forethought" connectives.
Third Edition (1975)
The Third edition was published with a first printing of 3,000 copies, including both hard and paper bindings. It was advertised in the August 1975 issue of Scientific American. According to James Cooke Brown, the printing sold out.
John Clifford notes that the author's address, as printed on the back of the book, was incorrect, which resulted in lost correspondence.
Changes to the language relative to the previous version include the specification of a system for "implicit quantification".
Fourth Edition (1989)
The Fourth Edition is (as of 2017) the last edition to be printed.
Changes to the language relative to the previous version include the new morphology rules (per the "Great Morphological Revolution") for the formation of "complex predicates" and loan-words, and a greatly expanded word list incorporating the letters that had been added to the language since the Third Edition: H (1977), Y (1982), Q/W/X (1986).
This edition also incorporated material from 1987's Notebook 3, establishing a provision for speaking of "universals and existentials by indefinite description". A similar facility had been described in the 1960 Scientific American article.
Also introduced in this edition were the "connective interrogative", "ha", as proposed by John Parks-Clifford in 1977, the "metaphorical predifier" "me" which had been developed in 1978 with input from Scott W. Layson and John Parks-Clifford, and the anaphoric use of letter variables, which had been suggested by Stephen Smith in 1979.
New scope delimiters ("cui", "cue", "geu") were added as the result of the 1977 discovery that "Pretty Little Girls' School" could not be unambiguously grouped as "(A(BC))D". Finally, a new chapter detailed a program for using loglan to test the Sapir-Whorf hypothesis.
Revised Fourth Edition (1999)
The Revised Fourth Edition was published to the Web, integrating material from Loglan Updater 1 (1996), which in turn compiled new prescriptions endorsed by The Loglan Academy ("La Keugru") since the publication of the Fourth Edition.
Changes to the language relative to the previous version include the reassignment of "me" as the "extensional predifier", a 1994 refinement proposed by Randall Holmes. A new word, "mea" was introduced to take over the role of "metaphorical predifier".