Le samedi 15 février 2014 10:55:19 UTC+9, xorxes a écrit :
On Fri, Feb 14, 2014 at 8:36 PM, guskant
<gusni...@gmail.com> wrote:
It is because the following proposition is given as an axiom in the universe of discourse (UD1) on the current topic.
P1:
ro'oi da poi ke'a me lo sidbo ku'o su'oi de zo'u de me da ijenai da me de
From P1 I get "no da me lo sidbo".
If another axiom that is equivalent to P3 were given on UD1, yes, we would get "no da me lo sidbo". However, we did not give P3 or the equivalent as an axiom on UD1.
In this universe of discourse, the following proposition is a theorem.
P2:
naku ro'oi da poi ke'a me lo sidbo zo'u lo sidbo cu me da
As long as talking about UD1, we are forced to think that P2, that is, there is no individual {lo sidbo}, because it is a proved theorem.
I don't see how P2 follows from P1.
Also, in P2, "lo sidbo" could not refer to a single individual, but it could refer to two individuals. Suppose it refers to two individual ideas I had this morning. Then P2 is true: It is not the case that for every X among those two ideas, those two ideas are among X" (in particular for each one of the ideas, the two ideas are not among it. You must have meant something else.
Here is the proof of P2.
da'i
ro'oi da poi ke'a me lo sidbo zo'u lo sidbo cu me da (to lo se sruma toi)
iseni'ibo
naku su'oi da poi ke'a me lo sidbo ku'o naku zo'u lo sidbo cu me da
iseni'ibo
naku su'oi da poi ke'a me lo sidbo zo'u naku lo sidbo cu me da
iseni'ibo
naku su'oi da zo'u da me lo sidbo ije naku lo sidbo cu me da
iseni'ibo
naku su'oi da zo'u da me lo sidbo ijenai lo sidbo cu me da (to lo bridi xi pa toi)
ita'o
ge
lo sidbo cu me lo sidbo (to lo se ckaji be zo me toi)
gi
ro'oi da poi ke'a me lo sidbo ku'o su'oi de zo'u de me da ijenai da me de (to P1 toi)
iseni'ibo
su'oi de zo'u de me lo sidbo ijenai lo sidbo cu me de (to lo bridi xi re toi)
iku'i
lo bridi xi re cu natfe lo bridi xi pa
iseni'ibo
naku ro'oi da poi ke'a me lo sidbo zo'u lo sidbo cu me da
uo
It is thus proved that {lo sidbo} is not an individual.
Moreover, it is also proved that {lo sidbo} is not individuals using a property of jo'u:
da'i
lo sidbo cu me A jo'u B ije A jo'u B cu me lo sidbo ({lo sidbo} is identical to A jo'u B)
ige
A me A jo'u B
gi
B me A jo'u B
iseni'ibo
ge
A me lo sidbo
gi
B me lo sidbo
i la'e di'u lu'u joi P1 cu nibli lo simsa be lo bridi xi re
iseni'ibo
ge
naku ro'oi da poi ke'a me A zo'u A cu me da
gi
naku ro'oi da poi ke'a me B zo'u B cu me da
uo
It is thus proved that {lo sidbo} is not individuals.
Because neither P1 nor P3 is tautology, we are not forced to think that one of them is always true for all the universes of discourse. We have freedom to choose non-logical axioms and a universe of discourse according to context.
Even granting that, I think that what we're missing is some motivation for such a seemingly strange universe of discourse. Are there any predicates in natlangs that tend to behave that way? My prediction is that if there was some predicate broda that tended to satisfy P1, it would quickly tend to be replaced by another brode such that ro'oi da poi proda ku'o su'o de poi brode zo'u de gunma da, and then "lo brode", which would have individual referents, would be used instead of "lo broda".
I understand that giving an axiom
{ro'oi da su'oi de ro'oi di poi ke'a me de zo'u de me di ije de me da}
(for all X there is Y such that Y is individual and Y {me} X)
is very useful, and also necessary for conforming to mereology with atoms.
Still, we cannot assert this proposition to be a common axiom to all the universes of discourse, because
"Something that needs to be noted in general: we, the BPFK, made a consensus decision that we do not make rulings on ontological or metaphysical issues."
http://www.lojban.org/tiki/How+to+use+xorlo
Asserting "ro'oi da su'oi de" as a common axiom is indeed an ontological commitment, and violates the principle of xorlo.