RUTH BARCAN MARCUS AND MODALITY (4): More ESSENTIALISM

Marcus wants to look more closely at how we attribute or give properties to things, and how we decide whether a property really belongs to a thing in every possible situation. The key question is this: when we say “x must have property P,” what exactly are we saying, and how should a logical language represent it?

She begins by noticing that ordinary everyday language is full of statements that look essentialist. For example, people often say “Gold must be a metal,” “Water must be H2O,” or “Socrates must be human.” These sound like strong statements, much stronger than ordinary facts such as “Gold is shiny.” When we say “Gold must be a metal,” we seem to be saying that something would stop being gold if it stopped being a metal. So the property of being a metal seems essential. The shininess of gold seems accidental, because you can imagine gold that is dull, as when it is in a powder. Marcus wants to explain how logic can respect these differences. She wants to show that essential attributions are neither magical nor mysterious. They can be represented by careful rules about how we use the word “necessarily” in combination with identity.

Remember that identity is treated as necessary. If a = b, then it is necessarily true that a = b. Now Marcus says: if x has an essential property P, then not only does x have P in the actual world, but in every possible situation where x exists, x also has P. So the statement “x has P” becomes a strict and stable fact about that object. The logic represents this by writing something like: “If x exists, then necessarily x has P.” She says that essential attributions are like very firm anchors. If a property is essential, you cannot pull it away without losing the object itself. Next she explains the difference between two ways of talking about properties. One way is purely linguistic. For example, you can define “bachelor” as “unmarried man.” Then “All bachelors are unmarried” is true just because that is what the word means. It is a meaning truth, not a deep truth about the world. A second way of talking about properties is metaphysical. For example, “Water is H2O” is not just about the meaning of the word “water.” Scientists discovered something about the real nature of water, and now we take that to be essential to it. Marcus says essential attributions belong to this second kind. They are not just word tricks. They are claims about the world itself. A good logical system must be able to handle both without mixing them up.

She spends some time criticising a mistake that appears in a lot of anti essentialist writing. Some philosophers thought that if you treat essential attributions as necessary, then you must be saying that everything is fixed by language. They imagined that the only way to make something necessary is by defining terms in a special way. Marcus says this is completely wrong. Logical necessity is not created by word meanings. Logical necessity in her system arises from identity and from the nature of the object. If something is that object, and that object has an essential property, then the necessity comes from the object, not from our linguistic choices. 

She then deals with another difficulty. If we treat essential properties very seriously, do we risk making everything essential, even silly properties? For example, your favourite toy car happens to be on your desk. Could we then say “It is essential to this toy car that it is on the desk”? Marcus says no. Essential attributions must be carefully separated from accidental properties. Logical systems that fail to mark this difference become trivial and unhelpful. The logic she prefers allows essential attributions but does not force accidental properties to turn essential. In fact, the logic actively prevents such mistakes. 

Quantifiers are expressions like “there is an x such that” and “for every x.” When we say “For every x, if x is gold, then x must be a metal,” we are saying something like “Being a metal is essential to gold.” Marcus shows that you cannot make sense of such statements unless you treat the identity of x as fixed across possible worlds. If you try to say “x is gold in this world, but in another possible world the same x is not a metal,” you get confusion about what the object is. The logic she builds insists that the quantifiers pick out the same objects in every possible situation where they exist. That makes essential attributions clean and understandable. She also confronts a well known objection. Some philosophers say that essentialism makes the world too rigid. They imagine a picture in which nothing could ever have been different. Marcus says this is not what essentialism commits you to at all. Essentialism says only that some properties cannot change without destroying the identity of the thing. Many properties can still change. You can grow, move, change jobs, change appearance, learn new skills, and so on. Essentialism does not deny change. It only marks a boundary between necessary features and variable ones. She thinks that without that boundary, our reasoning about objects becomes sloppy and confused. For example, if you say “Socrates might have been a robot,” you are no longer talking about Socrates. You are talking about some other possible creature. Essentialism helps logic keep track of when we are still talking about the same object and when we have drifted into talking about a different one.

She ties everything back to the structure of the modal logic she supports. Essential attributions are expressed by putting the necessity operator inside the scope of a quantifier but tied to the identity of the object. By doing this carefully, the logic can state things like “Socrates is essentially human” or “Gold is essentially a metal” in a way that is consistent, meaningful, and avoids the paradoxes that worried earlier philosophers. She even suggests that essential attributions may be one of the main reasons why we need modal logic at all. A logic without modal operators cannot reliably express the idea that some features are necessary for an object to be what it is.

So she thinks that essential attributions are not a strange addition made up by logic. They are already present in our ordinary thinking about objects. Marcus is simply giving a precise formal account of how to handle them. Without such a system, modal talk becomes either too weak or too confused. With a good system, we can reason clearly about objects, their identities, their possible variations, and the properties they must have. Essentialism, properly handled, strengthens logic rather than distorting it.