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Entry first published Sun Apr 24, 2016

Generic Generalizations
http://plato.stanford.edu/entries/generics/

INTRO: Generics are statements such as “tigers are striped”, “a duck lays eggs”, “the dodo is extinct”, and “ticks carry Lyme disease”. Generics express generalizations, but unlike quantified statements, generics do not carry information about how many members of the kind or category have the property. For example, if asked “how many ravens are black?” one could reply “all [or some, or most, etc.] ravens are black”, but one cannot felicitously reply with the generic “ravens are black” (Carlson 1977).

Generics have proved quite difficult to analyze semantically. For example, “dogs are mammals” seems to require for its truth that all dogs be mammals. “A tiger is striped” or “ravens are black”, however, are somewhat more forgiving, since they are compatible with the existence of a few stripeless tigers and white albino ravens. “Ducks lay eggs” and “a lion has a mane” are more forgiving still; these generics are true even though it is only the mature members of one sex that possess the relevant properties. Notice, however, that we do not accept “ducks are female”, even though every egg-laying duck is a female duck. Finally, we accept “ticks carry Lyme disease”, even though very few ticks (approximately one percent) actually have the property, while also rejecting “humans are right-handed”, when over ninety percent of humans are right-handed.

As these examples illustrate, generics are not equivalent in meaning to any of the quantifying determiners such as “all”, “some”, or “most”. They also differ in meaning from sentences containing adverbs of quantification (Lewis 1975) such as “generally”, “usually”, or “often”. For example, the generic “books are paperbacks” is false, yet the insertion of any of these adverbs of quantification would render the statement true: “books are generally/usually/often paperbacks”....



Substantive revision Mon Apr 18, 2016

Essential vs. Accidental Properties
http://plato.stanford.edu/entries/essential-accidental/

INTRO: The distinction between essential versus accidental properties has been characterized in various ways, but it is currently most commonly understood in modal terms: an essential property of an object is a property that it must have, while an accidental property of an object is one that it happens to have but that it could lack. Let’s call this the basic modal characterization, where a modal characterization of a notion is one that explains the notion in terms of necessity/possibility. In the characterization just given of the distinction between essential and accidental properties, the use of the word “must” reflects the fact that necessity is invoked, while the use of the word “could” reflects that possibility is invoked. The notions of necessity and possibility are interdefinable: to say that something is necessary is to say that its negation is not possible; to say that something is possible is to say that its negation is not necessary; to say that an object must have a certain property is to say that it could not lack it; and to say that an object could have a certain property is to say that it is not the case that it must lack it.

Many would say that each individual human could not fail to be human; if so, then the basic modal characterization counts the property of being human as an essential property of each human. And, too, many would say that although someone, say Socrates, is in fact fond of dogs, Socrates could have lacked that property; if that is right, then the basic modal characterization counts the property of being fond of dogs as an accidental property of Socrates.

A modal characterization of the distinction between essential and accidental properties is taken for granted in nearly all work in analytic metaphysics since the 1950s. Advocates of the modal characterization have included Ruth Barcan Marcus (1967) and Saul Kripke (1972/1980), among others. However, some other characterizations of the distinction (see §2) have recently gained currency. It is worth stressing here at the outset that although there is now some disagreement about how the distinction between essential and accidental properties is to be drawn, there is nevertheless some agreement about cases. Most would agree that however the distinction is drawn, it should come out that being human (or being human if existent) is an essential property of Socrates while being fond of dogs is a merely accidental property of Socrates.

Essentialism in general may be characterized as the doctrine that (at least some) objects have (at least some) essential properties. This characterization is not universally accepted (see §3), but no characterization is; and at least this one has the virtue of being simple and straightforward. As for specific essentialist claims, we have already encountered one—the claim that the property of being human is essential to Socrates. Another example is the claim that Socrates’s biological origin—Socrates’s parents, or more particularly, the sperm and egg from which Socrates arose—is essential to Socrates. The first example is a brand of sortal essentialism while the second is a brand of origin essentialism. Both of these kinds of essentialisms have figured prominently in the philosophical literature....