All the objects are red, so the group is red.
All the objects are small, but the group is not small.
Color is ___, while size is ___ .
I'm trying to remember the words for this distinction regarding properties and collections, but I am struggling to do so. The words are most frequently encountered in philosophy, I believe.
Materials and systems have what are called intensive and extensive properties. From Wikipedia:
Physical properties of materials and systems can often be categorized as being either intensive or extensive quantities, according to how the property changes when the size (or extent) of the system changes. According to IUPAC, an intensive property is one whose magnitude is independent of the size of the system. An extensive property is one whose magnitude is additive for subsystems.
An intensive property is a bulk property, meaning that it is a physical property of a system that does not depend on the system size or the amount of material in the system. Examples of intensive properties include temperature, T, refractive index, n, density, ρ, and hardness of an object, η (IUPAC symbols[1] are used throughout this article). When a diamond is cut, the pieces maintain their intrinsic hardness (until their size reaches a few atoms thick), so hardness is independent of the size of the system.
By contrast, an extensive property is additive for subsystems. This means the system could be divided into any number of subsystems, and the extensive property measured for each subsystem; the value of the property for the system would be the sum of the property for each subsystem. For example, both the mass, m, and the volume, V, of a diamond are directly proportional to the amount that is left after cutting it from the raw mineral. Mass and volume are extensive properties, but hardness is intensive....
The terms intensive and extensive quantities were introduced by Richard C. Tolman in 1917....
Examples of intensive properties include:
chemical potential, μ / color / concentration, c / density, ρ (or specific gravity) / magnetic permeability, μ / melting point and boiling point / molality, m or b / pressure, p / specific heat capacity, cp / specific volume, v / standard reduction potential, E° / temperature, T...
Examples of extensive properties include:
amount of substance, mol / energy, E / enthalpy, H / entropy, S / Gibbs energy, G / heat capacity, Cp / Helmholtz energy, A or F / internal energy, U / mass, m / volume, V
(bolding mine). 'Number of elements in a set' is obviously an extensive quantity.
A word that might be relevant to what you're seeking is emergent.
An emergent property is a property which a collection or complex system has, but which the individual members do not have.
In the case of your question, the "size" of the group is an emergent property. If you add enough small things together, you get a big group of things.
It's not a perfect match with your example: For instance, color and size could both be emergent, depending on the circumstances. If you make a grid of alternating black and white pixels and look at it from a distance, it could be perceived as "gray."
Another example where color forms an emergent property is in photomosaics.
However, it seems relevant enough to your question to be worth bringing to attention.
