10.23. Tenses versus modals

Grammatically, every use of tenses seen so far is exactly paralleled by some use of modals as explained in Chapter 10. Modals and tenses alike can be followed by sumti, can appear before the selbri, can be used in pure and mixed connections, can participate in JAI conversions. The parallelism is perfect. However, there is a deep difference in the semantics of tense constructs and modal constructs, grounded in historical differences between the two forms. Originally, modals and tenses were utterly different things in earlier versions of Loglan; only in Lojban have they become grammatically interchangeable. And even now, differences in semantics continue to be maintained.

The core distinction is that whereas the modal bridi

Example 10.171. 


I like you because you like me.

places the le nu sumti in the x1 place of the gismu mukti (which underlies the modal mu'i), namely the motivating event, the tensed bridi

Example 10.172. 


I like you after you like me.

places the le nu sumti in the x2 place of the gismu balvi (which underlies the tense ba), namely the point of reference for the future tense. Paraphrases of Example 10.171 and Example 10.172, employing the brivla mukti and balvi explicitly, would be:

Example 10.173. 


Your liking me is the motive for my liking you.


Example 10.174. 


My liking you follows (in time) your liking me.

(Note that the paraphrase is not perfect due to the difference in what is claimed; Example 10.173 and Example 10.174 claim only the causal and temporal relationships between the events, not the existence of the events themselves.)

As a result, the afterthought sentence-connective forms of Example 10.171 and Example 10.172 are, respectively:

Example 10.175. 

Ilikeyou.[That-is] Becauseyoulikeme.

Example 10.176. 


In Example 10.175, the order of the two bridi mi nelci do and do nelci mi is the same as in Example 10.171. In Example 10.176, however, the order is reversed: the origin point do nelci mi physically appears before the future-time event mi nelci do. In both cases, the bridi characterizing the event in the x2 place appears before the bridi characterizing the event in the x1 place of mukti or balvi.

In forethought connections, however, the asymmetry between modals and tenses is not found. The forethought equivalents of Example 10.175 and Example 10.176 are

Example 10.177. 



Example 10.178. 



The following modal sentence schemata (where X and Y represent sentences) all have the same meaning:

X .i BAI bo Y
BAI gi Y gi X
X BAI le nu Y

whereas the following tensed sentence schemata also have the same meaning:

X .i TENSE bo Y
TENSE gi X gi Y
Y TENSE le nu X

neglecting the question of what is claimed. In the modal sentence schemata, the modal tag is always followed by Y, the sentence representing the event in the x1 place of the gismu that underlies the BAI. In the tensed sentences, no such simple rule exists.