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

7. Predication/sentence abstraction

The following cmavo is discussed in this section:

du'u    NU  predication abstraction

There are some selbri which demand an entire predication as a sumti; they make claims about some predication considered as a whole. Logicians call these the “propositional attitudes”, and they include (in English) things like knowing, believing, learning, seeing, hearing, and the like. Consider the English sentence:

✥7.1  I know that Frank is a fool.

How's that in Lojban? Let us try:

✥7.2  mi djuno le nu la frank. cu bebna [kei]
I know the event of Frank being a fool.

Not quite right. Events are actually or potentially physical, and can't be contained inside one's mind, except for events of thinking, feeling, and the like; ✥7.2 comes close to claiming that Frank's being-a-fool is purely a mental activity on the part of the speaker. (In fact, ✥7.2 is an instance of improperly marked “sumti raising”, a concept discussed further in c11-§10).

Try again:

✥7.3  mi djuno le jei la frank. cu bebna [kei]
I know the truth-value of Frank being a fool.

Closer. ✥7.3 says that I know whether or not Frank is a fool, but doesn't say that he is one, as ✥7.1 does. To catch that nuance, we must say:

✥7.4  mi djuno le du'u la frank. cu bebna [kei]
I know the predication that Frank is a fool.

Now we have it. Note that the implied assertion “Frank is a fool” is not a property of “le du'u” abstraction, but of “djuno”; we can only know what is in fact true. (As a result, “djuno” like “jei” has a place for epistemology, which specifies how we know.) ✥7.5 has no such implied assertion:

✥7.5  mi kucli le du'u la frank. cu bebna [kei]
I am curious about whether Frank is a fool.

and here “du'u” could probably be replaced by “jei” without much change in meaning:

✥7.6  mi kucli le jei la frank. cu bebna [kei]
I am curious about how true it is
    that Frank is a fool.

As a matter of convenience rather than logical necessity, “du'u” has been given an x2 place, which is a sentence (piece of language) expressing the bridi:

x1 is the predication (the bridi), expressed in sentence x2

7.6.5)  la djan. cusku
    le se du'u
        la djordj. klama le zarci [kei]
John expresses
    the sentence-expressing-that
        George goes-to the store
John says that George goes to the store.

✥7.6 differs from

✥7.7  la djan cusku
    lu la djordj. klama le zarci li'u
John expresses,
    quote, George goes to the store, unquote.
John says “George goes to the store”.

because ✥7.7 claims that John actually said the quoted words, whereas ✥7.6 claims only that he said some words or other which were to the same purpose.

“le se du'u” is much the same as “lu'e le du'u”, a symbol for the predication, but “se du'u” can be used as a selbri, whereas “lu'e” is ungrammatical in a selbri. (See Chapter 5 for a discussion of “lu'e”.)