Necessary properties vs. essential properties?

[Philo]

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Philo, and 1's&0's, elaborate please?

It seems that if someone (me) has no frame of referance as to the OP the answer is, 'no/symantics riddle'.

Some thinking from those that seem to believe they know the answer please...?

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If p has a property necessarily then it is not possible for p to not have that property. In other words, in any possible world p has that property.

If p has a property essentially then p cannot exist without having that property. For p to lose that property is for p to cease to exist.

The philosophical issue is certainly not a question of semantics, but again, the traditional answer has usually been yes.

See Kripke's Naming and Necessity and "Identity and Necessity."

[vhawk01]

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Philo, and 1's&0's, elaborate please?

It seems that if someone (me) has no frame of referance as to the OP the answer is, 'no/symantics riddle'.

Some thinking from those that seem to believe they know the answer please...?

[/ QUOTE ]

If p has a property necessarily then it is not possible for p to not have that property. In other words, in any possible world p has that property.

If p has a property essentially then p cannot exist without having that property. For p to lose that property is for p to cease to exist.

The philosophical issue is certainly not a question of semantics, but again, the traditional answer has usually been yes.

See Kripke's Naming and Necessity and "Identity and Necessity."

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So there is no way this guy is giving away and free As and this is just a trick. What a cool way to get college kids interested in philosophy! I can just imagine that most kids in the class were thinking "Oh good one Mr. X, you really got me, hahaha tell me more about philosophy!" and not "Nice one douchebag stfu."

[Siegmund]

Disclaimer: I am not a philosopher, except insofar as I am part mathematician.

I would prefer the answer to be no. It is useful to distinguish between the (often quite long) list of properties that something has, and the (often much shorter) list of properties which are required for a minimal description of what something is.

Here's an example:

Suppose I want to know if some positive integer N is a prime number or not.

Any statement S such that S is true for all primes gives rise to a necessary condition, via its contrapositive: it is necessary for S to be true for N to be prime (not-S implies N is not prime.)

For instance, it is necessary for N not end in zero (i.e. to not be divisible by ten), for N to be a prime. You can see in an instant that 32,650 is not a prime number, because it ends in ten. However, despite this being a necessary property for being prime, it doesn't tell you a blessed thing about what prime numbers are. The essential property of a prime is that it is not divisible by any number smaller than itself, except 1. The fact that 7 is not divisible by 10 is completely irrelevant, and the fact that 237 is not divisible by 10 does not take you very far toward knowing if 237 is prime or not.

One might, for instance, say that the definition of something is an enumeration of its essential properties (from which all the rest of the necessary properties can be derived as needed.) There may be more than one such enumeration - but the key ingredient is that if anything be taken away from such a list of essential properties, the remaining properties on the list are insufficient to determine whether or not something does or doesn't satisfy the definition.

I don't know if philosophy has the notion of a "minimal list of necessary properties" or not. If not, seems like they should.

[Philo]

There is a tradition in philosophy that makes this distinction. On this reading an object's essential properties are those properties that mark the essence of an object, so that the essential property of a prime number would be, as you say, that it is not divisible by any number smaller than itself, except 1.

[KLJ]

this is actually really interesting, albeit confusing

[PairTheBoard]

I'm thinking the best answer might be, not necessarily.

If Philo and Siegmund are in agreement about the word "essential" meaning "necessary and sufficient" as the phrase is used in mathematics, then I'm on the same page as them. It's then conceivable that an object might exist whose necessary properties are in fact sufficient as well - although as in Sigmund's example of prime numbers that's certainly not true in general.

However, what about a collection of properties which when taken together are necessary and sufficient. Are they considered "essential properties"? If so, does the collection have to be minimal? If not, the collection of all necessary properties would contain any such necessary and sufficient collection and thus be essential. If the collection does have to be minimal, then it's conceivable that an object might exist such that any necessary property belongs to some minimal necessary and sufficient collection of properties. Thereby making it an essential property wrt that collection.

So I'm thinking the best answer is, not necessarily. I can see such an answer being rarely given by a student, thus protecting the teacher's offer of an A. It also has a neat twist to it wrt to the question.

PairTheBoard

[chezlaw]

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So I'm thinking the best answer is, not necessarily.

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essentially the same but not necessarily the same?

chez

[PairTheBoard]

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So I'm thinking the best answer is, not necessarily.

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essentially the same but not necessarily the same?

chez

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Not necessarily essentially the same.

PTB

[chezlaw]

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So I'm thinking the best answer is, not necessarily.

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essentially the same but not necessarily the same?

chez

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Not necessarily essentially the same.

PTB

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essentially essentially the ...

chez

[tame_deuces]

To me it still stands as nothing but a semantic riddle. They aren't the same but what they name are the same properties. So both yes and no are wrong answers, and you can kill any answer .