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NATURAL_KINDS
February 2-12, 2021
W.V. Quine's essay on "Natural Kinds" begins
with some excellent observations: our ability A grasp of similarity is
to percieve "similarity" is fundamental to necessary for confirmation
our understanding, and is self-evidently an of induction.
extremely common human capability-- arguably
it's used heavily in language acquistion, The way I would put it:
where similarities in both the sounds a child all scientific work
hears and the surrounding circumstances requires an ability
have to be identified and associated with each to choose an appropriate
other. way of categorizing
data.
The concept of similarity is,
however, remarkably difficult to
pin down in any coherent way--
what makes one similarity Quine makes the point that
significant (or potentially "similarity" is easily as
significant) and another an important as fundamental
obviously spurious trivialty? logical concepts like
"not", "and" and "or",
but far more difficult to
talk about precisely.
Quine tries to shoot down a
possible criteria of similarity:
if you have things categorized
into different sets (according to
different "properties"), then you
could count the number of sets I think this is funny
that B belongs to that A also because I've used this idea
belongs to: could the in software design, to
number-of-sets-in-common be a avoid randomly choosing
good proxy for similarity? photos that seem "samey".
Quine asserts that a principle
of set theory is that sets can
be formed on any and every
random criteria: if the numbers The approach can be salvaged if
of sets involved are infinite you've chosen a set of "relevant"
then it would seem to be properties to use for set
improbable this proceedure could formation-- which is to say you're
be made to work. going to consider only a sub-set
of sets along some "sensible"
categorization scheme.
I have the sense that Quine
is working up a concept of That all just pushes the
a "kind" that's very problem around, of course,
similar to what we might and (I presume) this is where
call a "fuzzy set". Quine is going: it's an
absolute necessity to work
In Raku, fuzzy sets are with some sort of "a priori"
called "Mixes", which knowledge of what properties
might seem puzzling, but are likely to be important.
isn't *terribly* so. "Natural kinds".
Though rather than focusing on
the fuzziness of the boundaries
the initial motivation behind the Some of the issues on Quine's
Kind idea seems to have more to mind have to do with things
do with that issue of allowed Set that were common knowledge in
definitions being infinite. his world but not in mine:
Quine is going to restrict the there's a distinction between
numbers of Kinds somehow properties and sets, you see,
(presumably, naturally). one is *intensional* and the
other is *extensional*, and
Or so I presumed: the title "intensional" and "extensional"
phrase is not actually used strike me as properties that
in the conclusion of the would only seem natural to the
essay. set of human beings called
Philosophers.
From looking at some other material,
I gather that for Quine the
"extensional" is what you refer to
Quine also makes an but the "intensional" is what you
allusion to _respects_, mean. E.g. you might say "prominent
which evidentally is the orange psychotics" as a way of
idea that different refering to a particular human being.
things can be similar in
different ways, in How that works out to a difference between
different "respects". sets and properties, I could not tell you.
Maybe, a property is what you really care
I don't see how it helps about, and that determines the division
to point that out, except into sets?
to make it explicit that
we're casually doing some
very fancy dancing when
we identify patterns.
In the conclusion of the essay, Quine begins musing
about how in specific fields such as Chemistry the
idea of "similarity" is very precisely defined.
He speculates that there might be some way of
firming up the concept of similarity in general,
a "cosmic similarity" that's not restricted to
a particular field.
There's also some speculation about
possible fallbacks that might be of
interest-- one gathers that Quine did Quine mentions with
not really believe in his cosmic approval some examples
similarity-- could it be that there from the natural
are different kinds of similarity, sciences where
and, for example, different fields perception of similarity
might be classified by the types of has been adjusted in the
similarity that seem appropriate for light of new evidence.
those fields?
"Fishes" once included
Kinds of similarity, whales and dolphins,
sets of fields. now they don't: the
similarity is regarded
as superficial and
So: "Natural Kinds"? That might be deceptive.
a sort of play on words: in the natural
sciences there's a kind of kinds that That's an obvious enough
seems much different than the kinds of example, I would say,
kinds that seem natural to us. but I hadn't thought
about it in some time.
CRYSTALLINE_DEFINITION
It's not hard to think
of similar examples:
spiders were once like
ants, now they're not.
So: our understanding
of the world-- our
conceptual framework--
has changed the way we
percieve it.
In this case Quine
approves, there's
another place where
he disagees with
this on principle:
phenomena first,
theory afterwards.
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