Re: A Fuzzy Ship from Theseus

[ucleaar <ucleaar@UCL.AC.UK>]

Steven:
> >I believe in fuzzy categories, and I recognize that this example is
> >from time to time used to exemplify the notion, but I think it is
> >not in the least fuzzy. Eagles, pigeons, penguins are all indubitably
> >birds, and bats, squirrels are indubitably not birds. These are
> >on a TYPICALITY GRADIENT [emphasis, not yelling] but not a
> >MEMBERSHIP GRADIENT. Contrast this with the category Square: the
> >further something is from having four sides of equal length and four
> >angles of 90 degrees, the less it is a square, but it isn't possible
> >to say when it becomes definitely not a square. A category has gradient
> >membership iff it has defining features.
> >This is not necessarily the standard view, but at any rate it's what I
> >teach my students.
> Sure, eagles, pigeons, penguins, and ostriches are genetically birds. I
> certainly think genetics are important. But to me birdishness is more than
> genes. An eagle gets a higher birdish score, because it swoops about so
> birdishly, displaying several different modes of flight-soaring, diving,
> climbing. Pigeons seem to fly mainly to avoid being stepped on. Penguins
> fly, sure, but underwater! Ostriches just run.

Those students' experiments have confirmed that if you ask people "Is an
ostrich a bird?" and let their answer be somewhere on a scale from "yes,
definitely" through "yes, probably", "not sure", to "no, definitely
not", they'll say "yes, definitely".  In contrast, if you show them a
wonky, somewhat irregular quadrilateral & ask "Is this a square?",
they'll mostly answer "not sure".

If, however, you ask people "Is an ostrich a typical bird", they'll all
say "no, definitely not".  And if you ask someone to think of a bird,
they'll not think of an ostrich.

In sum, it is necessary to distinguish the matter of how much X is a
member of category Y from the matter of how central a member of Y X is.

> Imagine that I incrementally replace an eagle's genes with the
> analogous iguana genes. With which substitution does the eagle
> abruptly cease being a bird?

Since we don't have much experience of such phenomena, I'm rather short
of reliable intuitions on this.  But I think it might show that in
principle the category Bird does have a defining feature, namely
possession of bird genes, and therefore has gradient membership.

I said:
> For meanings like "ish", "sort of". I agree {jei} doesn't really
> have the right syntax to do the job. Something in NA would be more
> appropriate.

Jorge:
> je'ucai         absolutely true
> je'usai
> je'u
> je'uru'e
> je'ucu'i
> je'unairu'e
> je'unai
> je'unaisai
> je'unaicai      absolutely false

These have the right meaning.  Do we know how they interact with {na}
and {jaa}?

Dylan:
> Aren't {traji}, {banli}, {mutce}, {nutli}, and {milxe} just what's wanted?

They may have the right meaning, but I guess you'd use them in tanru,
which are doomed to ineluctable vagueness.

> > The relevant distinction is the structure of the scale. Ni is bounded
> > at the negative end of the scale and unbounded at the positive end of
> > the scale. True/false in fuzzy logic is bounded at both ends of the
> > scale. True/false, correct/incorrect in English lexical semantics is
> > bounded at the positive (true/correct) end of the scale and unbounded
> > at the negative end. Whichever scale structure you choose for true/false,
> > it's different from the scale structure for ni.
> Hum.  The reason {lo ni gusni} is bounded on one end is a absolute
> minimum to the amount of brightness: total darkness, while the
> absolute maximum is far beyond our experience.  (At a certain point
> the energy density of the photons would create a black hole, I
> believe.)  But this is particular to {gusni}.

That's true, I think.  The scale structure of ni but not of jei is
affected by the semantics of the subordinate bridi.

> Is {lo jei broda} equivalent to {lo ni lodu'u broda cu fatci}?

to {lo ni loe duu broda cu jeftu} is better, I think, but yes.  The
redundancy of {jei} has been remarked upon before.

> Would {ka} be more appropriate?

I don't immediately see why.

> Is the difference that truth values are usually quite near one end of
> the scale?

The difference between what?

> Wow, do we have a live professor on the list?  You teach logic, I take
> it?

God no. Linguistics. I don't know anything about logic except what
I glean from jbomri. Pc is the logician.
---
And noi nae logji