Chapter 11: Events, Qualities, Quantities, And Other Vague Words: On Lojban Abstraction

10. Lojban sumti raising

The following cmavo are discussed in this section:

tu'a    LAhE    an abstraction involving
jai JAI abstraction conversion

It is sometimes inconvenient, in a situation where an abstract description is logically required, to express the abstraction. In English we can say:

✥10.1    I try to open the door.

which in Lojban is:

✥10.2    mi troci le nu
    [mi] gasnu le nu
        le vorme cu karbi'o
I try the event-of
    (I am-agent-in the event-of
        (the door open-becomes)).

which has an abstract description within an abstract description, quite a complex structure. In English (but not in all other languages), we may also say:

✥10.3    I try the door.

where it is understood that what I try is actually not the door itself, but the act of opening it. The same simplification can be done in Lojban, but it must be marked explicitly using a cmavo. The relevant cmavo is “tu'a”, which belongs to selma'o LAhE. The Lojban equivalent of ✥10.3 is:

✥10.4    mi troci tu'a le vorme
I try some-action-to-do-with the door.

The term “sumti-raising”, as in the title of this section, signifies that a sumti which logically belongs within an abstraction (or even within an abstraction which is itself inside an intermediate abstraction) is “raised” to the main bridi level. This transformation from ✥10.2 to ✥10.4 loses information: nothing except convention tells us what the abstraction was.

Using “tu'a” is a kind of laziness: it makes speaking easier at the possible expense of clarity for the listener. The speaker must be prepared for the listener to respond something like:

✥10.5    tu'a le vorme lu'u ki'a
something-to-do-with the door [terminator] [confusion!]

which indicates that “tu'a le vorme” cannot be understood. (The terminator for “tu'a” is “lu'u”, and is used in ✥10.5 to make clear just what is being questioned: the sumti-raising, rather than the word “vorme” as such.) An example of a confusing raised sumti might be:

✥10.6    tu'a la djan. cu cafne
something-to-do-with John frequently-occurs

This must mean that something which John does, or which happens to John, occurs frequently: but without more context there is no way to figure out what. Note that without the “tu'a”, ✥10.6 would mean that John considered as an event frequently occurs — in other words, that John has some sort of on-and-off existence! Normally we do not think of people as events in English, but the x1 place of “cafne” is an event, and if something that does not seem to be an event is put there, the Lojbanic listener will attempt to construe it as one. (Of course, this analysis assumes that “djan.” is the name of a person, and not the name of some event.)

Logically, a counterpart of some sort is needed to “tu'a” which transposes an abstract sumti into a concrete one. This is achieved at the selbri level by the cmavo “jai” (of selma'o JAI). This cmavo has more than one function, discussed in Chapter 9 and Chapter 11; for the purposes of this chapter, it operates as a conversion of selbri, similarly to the cmavo of selma'o SE. This conversion changes

✥10.7    tu'a mi rinka
    le nu do morsi
something-to-do-with me causes
    the event-of you are-dead
My action causes your death.


✥10.8    mi jai rinka le nu do morsi
I am-associated-with causing the event-of your death.
I cause your death.

In English, the subject of “cause” can either be the actual cause (an event), or else the agent of the cause (a person, typically); not so in Lojban, where the x1 of “rinka” is always an event. ✥10.7 and ✥10.8 look equally convenient (or inconvenient), but in making descriptions, ✥10.8 can be altered to:

✥10.9    le jai rinka
    be le nu do morsi
that-which-is associated-with causing
    (the event-of your death)
the one who caused your death

because “jai” modifies the selbri and can be incorporated into the description — not so for “tu'a”.

The weakness of “jai” used in descriptions in this way is that it does not specify which argument of the implicit abstraction is being raised into the x1 place of the description selbri. One can be more specific by using the modal form of “jai” explained in Chapter 9:

✥10.10  le jai gau rinka
    be le nu do morsi
that-which-is agent-in causing
    (the event-of your death)