What is the main claim of the passage?

Vague words have no sharp boundary, so lines must be defended by their usefulness. (The last paragraph draws the conclusion: the line is arbitrary, and it must be defended by what it does for us.)

Where does the word sorites come from?

The Greek word for heap. (The first paragraph says the Greeks named it the sorites, from their word for heap.)

According to the passage, why is a law that fixes an exact age for adulthood arbitrary?

Growing up happens in small degrees with no natural cut-off point. (Adult is listed as a vague term, and the passage says a law must draw a line that reality does not contain.)

In this passage, arbitrary means

fixed at a point that nature does not decide for us. (The line is called arbitrary right after the claim that reality contains no such line, so nothing in nature fixes it.)

Where The Heap Ends: Level 5 Reading Comprehension Questions

Take ten thousand grains of sand piled on a table. That is a heap. Remove one grain and it is still a heap, since a single grain cannot be the difference between a heap and no heap. Apply that reasonable-looking rule again and again, and it carries you, one harmless step at a time, to the claim that one grain is a heap. The ancient Greeks named this the sorites, from their word for heap, and it has resisted easy solutions for well over two thousand years.

Each part of the argument looks safe on its own. The starting case is obvious, the final case is absurd, and every step between them is one that nobody wants to reject. Something must therefore be wrong with an assumption we never stated: that a vague word marks a sharp line somewhere, waiting to be discovered.

The paradox is not a trick about sand. It appears wherever consequences are attached to vague terms, such as bald, poor, dangerous, or adult. A law must draw a line that reality does not contain, and the line will be arbitrary. That is not a reason to draw no line. It is a reason to defend a line by what it does for us, rather than by pretending that nature marked the spot in advance.

Comprehension questions