The essence of water was revealed by science to be H₂O. What does this best illustrate about essential properties?
AEssential properties must be known before empirical investigation, since they define what a thing is
BEssence is a linguistic convention — what counts as essential depends on how speakers use the word 'water'
CEssential properties can be discovered a posteriori through scientific investigation, independent of how the term is ordinarily used
DOnly mathematical entities have genuine essences; natural kinds like water are too complex to have essential properties
Kripke and Putnam argued that natural kinds have de re essences discoverable by science. The essence of water is H₂O — not because speakers mean H₂O when they say 'water,' but because H₂O is what water actually is, in every possible world where water exists. This is a posterior discovery, not a conceptual truth. The common misconception is that essences must be knowable a priori from definitions; in fact, scientific investigation can reveal essences that ordinary language conceals.
Question 2 Multiple Choice
Which of the following is an intrinsic property of a gold atom, as opposed to a relational or extrinsic property?
ABeing the most expensive element in the laboratory
BHaving atomic number 79
CBeing stored in a particular vault
DBeing worth more than silver per gram today
An intrinsic property is one a thing has in virtue of itself, independently of its relations to other things. Atomic number 79 is intrinsic to gold: it belongs to each gold atom regardless of where it is, who owns it, or what else exists. The other options are relational — they depend on context, comparison, or external facts. The distinction between intrinsic and extrinsic is crucial for identity and individuation: when asking what makes something the kind of thing it is, we appeal to its intrinsic nature, not its accidents of circumstance.
Question 3 True / False
If a property is essential to a thing, that thing possesses the property in every possible world in which it exists.
TTrue
FFalse
Answer: True
This is precisely the modal characterization of essential properties: they are those the thing has necessarily, across all possible worlds where it exists. Water is H₂O in every possible world; a triangle has three sides in every possible world; being a prime is essential to the number 7. This is what distinguishes essential from accidental properties — accidental properties can vary across possible worlds (this shirt could have been blue), while essential properties cannot (this triangle could not have four sides).
Question 4 True / False
A thing's accidental properties are those it cannot lose without ceasing to exist.
TTrue
FFalse
Answer: False
This description fits essential properties, not accidental ones. Accidental properties are precisely those a thing can gain or lose while remaining the same thing — they are contingent. This shirt is red (accidentally) but could have been blue; Socrates was snub-nosed (accidentally) but could have had a different nose. Essential properties are those a thing cannot lack while remaining itself. Confusing accidental with 'unimportant' or 'changeable-while-preserving-existence' reverses the distinction.
Question 5 Short Answer
What distinguishes an essential property from an accidental one, and why does the distinction matter philosophically?
Think about your answer, then reveal below.
Model answer: An essential property is constitutive of what a thing is — the thing cannot exist without it, and losing it means the thing becomes something else entirely. An accidental property is one the thing happens to have but could lack while remaining the same thing. The distinction matters because: (1) identity criteria depend on it — what makes something the very same thing over time or across possible worlds; (2) natural kind classification requires it — species and chemical kinds are unified by shared essences, not shared accidents; (3) genuine definition requires it — a real definition captures the essence, while listing accidents is merely description.
The essential/accidental distinction is ancient (Aristotle) but was given a modern modal formulation by Kripke: essential properties are necessary (held in all possible worlds where the thing exists), accidental properties are contingent. This connects metaphysics to modal logic and philosophy of language, giving precise formal content to an intuitive distinction.