FAQ: What is the difference between Loglan and Lojban?

[pycyn@aol.com]

I need this vetted before I can go on with another summary: additions, 
subtractions, total revisions? tone? tune?

First, what is the same? Both derive from the work of the late Dr.
James Cooke Brown, beginning about 1955 and first published in a
1960 Scientific American. In the late 1980s, they separated. Loglan
is being continually developed by The Loglan Institute, essentially Dr.
Brown and an ever changing group of volunteers around him. Lojban
was developed and base-lined by the Logical Language Group, Bob
LeChevalier, John Cowan, and a growing group of volunteers who
interact over the internet. Lojban thus begins with the state of Loglan
in about 1986 and was developed to meet the specs of that language
more adequately. Loglan grew from that same base in a more
personal way, meeting new ideals as they occurred to Dr. Brown
over the years. As noted, Lojban has a complete base-lined grammar
and vocabulary and has had for nearly a decade; Loglan does not
have any complete versions and is constitutionally open to constant
modification.

Their common heritage is a grammar based upon an applied second
order predicate logic with identity and descriptions. In both this base
has been modified to allow full conversational capacity: questions,
commands, expressions of emotion, hypothetical claims, and so on. 
It has also been modified in the direction of conversational efficiency:
complex sentences can be reduced to complex parts, pronouns
function across sentence boundaries, second order features are
reduced to first order (predicates used as arguments become terms so
that second order predicates appear as first order), and a variety of
"abbreviations" (from the point of view of logical notation) are used,
pretty much the same in both languages.

The fundamental content vocabulary, the primitive predicates, of both
langauges are restricted to the same patterns in both (CCVCV or
CVCCV) and are constructed by an algorithm that is aimed at
maximizing the recognizability of the word to most speakers by
combining patterns from the corresponding words in the major
languages of the world. The sounds of the two languages are almost
exactly the same, though somewhat differently represented. For the
most part, the meanings of the basic words are the same, defined by a
basic idea and a place structure for arranging one to five arguments
around within that idea. Some of the ideas are different and the
arrangement of terms is often changed in the later places, but there
remains a high degree of comparability here.
The rules for making new predicates from the primitives are pretty
much the same at the basic level, with some differences (reflecting
also differences in orthography) in more complex cases. 
The rest of the fundamental vocabulary: logical words and emotional,
and other expressive forms and devices for collapsing logical
complexities follow similar patterns in the two langages, but differ
markedly in detail -- both in what forms occur in each type and in the
exact grammatical details of the forms. Generally, Lojban has been
more prolific in each area and has more detailed grammatical
definitions of each class.

The miost immediately obvious difference between the two, perhaps,
is in the fundamental vocabulary. Because Lojban was constructed
when TLI claimed a copyright on the shape of the words, the non-
content vocabulary is almost totally different, even when there is an
exact match in meaning. The content words are also almost always
different, in this case not only to avoid copyright problems but
because the algorithm for forming words was applied to a different
set of languages, with different weights (the major languages in order
in 1980 rather than 1950) and occasionally with a different selection
of the best word from a langauge to represent a concept. In addition,
the need for forms to be used in constructing compound was built
into the algorithm for Lojban in the beginning but added in Loglan
too late to affect most primitives.

The upshot of all this is probably that, although a Lojban and a Loglan
translation of a passage would appear very different on the surface, there is 
a pretty regular -- if not quite automatic -- procedure for turning one into 
the other. Since the Loglan grammar is neither complete nor publicly 
available, it is not quite clear whether this is completely true, but it 
clearly is for a great part of the langauge. It is also probably the case 
that the Loglan to Lojban translations are slightly easier than the reverse 
because of the greater variety of conversational words in Lojban, which may 
require special treatment in turning into Loglan.