Chapter 10: Imaginary Journeys: The Lojban Space/Time Tense System
The following cmavo are discussed in this section:
ca'a CAhA actually is ka'e CAhA is innately capable of nu'o CAhA can but has not pu'i CAhA can and has
Lojban bridi without tense markers may not necessarily refer to actual events: they may also refer to capabilities or potential events. For example:
✥19.1 ro datka cu flulimna all ducks are-float-swimmers All ducks swim by floating.
is a Lojban truth, even though the colloquial English translation is false or at best ambiguous. This is because the tenseless Lojban bridi doesn't necessarily claim that every duck is swimming or floating now or even at a specific time or place. Even if we add a tense marker to ✥19.1,
✥19.2 ro datka ca flulimna all ducks [present] are-float-swimmers. All ducks are now swimming by floating.
the resulting ✥19.2 might still be considered a truth, even though the colloquial English seems even more likely to be false. All ducks have the potential of swimming even if they are not exercising that potential at present. To get the full flavor of “All ducks are now swimming”, we must append a marker from selma'o CAhA to the tense, and say:
✥19.3 ro datka ca ca'a flulimna all ducks [present] [actual] are-float-swimmers All ducks are now actually swimming by floating.
A CAhA cmavo is always placed after any other tense cmavo, whether for time or for space. However, a CAhA cmavo comes before “ki”, so that a CAhA condition can be made sticky.
✥19.3 is false in both Lojban and English, since it claims that the swimming is an actual, present fact, true of every duck that exists, whereas in fact there is at least one duck that is not swimming now.
Furthermore, some ducks are dead (and therefore sink); some ducks have just hatched (and do not know how to swim yet), and some ducks have been eaten by predators (and have ceased to exist as separate objects at all). Nevertheless, all these ducks have the innate capability of swimming — it is part of the nature of duckhood. The cmavo “ka'e” expresses this notion of innate capability:
✥19.4 ro datka ka'e flulimna all ducks [capable] are-float-swimmers. All ducks are innately capable of swimming.
Under some epistemologies, innate capability can be extended in order to apply the innate properties of a mass to which certain individuals belong to the individuals themselves, even if those individuals are themselves not capable of fulfilling the claim of the bridi. For example:
✥19.5 la djan. ka'e viska John [capable] sees. John is innately capable of seeing. John can see.
might be true about a human being named John, even though he has been blind since birth, because the ability to see is innately built into his nature as a human being. It is theoretically possible that conditions might occur that would enable John to see (a great medical discovery). On the other hand,
✥19.6 le cukta ka'e viska The book [capable] sees. The book can see.
is not true in most epistemologies, since the ability to see is not part of the innate nature of a book.
Consider once again the newly hatched ducks mentioned earlier. They have the potential of swimming, but have not yet demonstrated that potential. This may be expressed using “nu'o”, the cmavo of CAhA for undemonstrated potential:
✥19.7 ro cifydatka nu'o flulimna all infant-ducks [can but has not] are-float-swimmers. All infant ducks have an undemonstrated potential for swimming by floating. Baby ducks can swim but haven't yet.
Contrariwise, if Frank is not blind from birth, then “pu'i” is appropriate:
✥19.8 la frank. pu'i viska Frank [can and has] sees. Frank has demonstrated a potential for seeing. Frank can see and has seen.
Note that the glosses given at the beginning of this section for “ca'a”, “nu'o”, and “pu'i” incorporate “ca” into their meaning, and are really correct for “ca ca'a”, “ca nu'o”, and “ca pu'i”. However, the CAhA cmavo are perfectly meaningful with other tenses than the present:
✥19.9 mi pu ca'a klama le zarci I [past] [actual] go-to the store. I actually went to the store. ✥19.10 la frank. pu nu'o klama le zdani Frank [past] [can but has not] goes-to the store. Frank could have, but will not have, gone to the store (at some understood moment in the future).
As always in Lojban tenses, a missing CAhA can have an indeterminate meaning, or the context can be enough to disambiguate it. Saying
✥19.11 ta jelca That burns/is-burning/might-burn/will-burn.
with no CAhA specified can translate the two very different English sentences “That is on fire” and “That is inflammable.” The first demands immediate action (usually), whereas the second merely demands caution. The two cases can be disambiguated with:
✥19.12 ta ca ca'a jelca That [present] [actual] burns. That is on fire.
✥19.13 ta ka'e jelca That [capable] burns. That is capable of burning. That is inflammable.
When no indication is given, as in the simple observative
✥19.14 fagri fire
the prudent Lojbanist will assume the meaning “Fire!”