Recently I thought about how sometimes objects can have several different parameters assigned to the single property and other-times not. For Example:

When we say that object is green and big no controversy occurs. But when we say that objects is small and big controversy occurs, that it is because small is the opposite of big. But when I say the object is green and purple, controversy occurs as well. But if you define purple as not green, then you might say the object is purple and blue. But it still is controversial.

Then we say there are some properties, like size and color. So, an object in the whole can't have two different values of the same property. But how do we know that two values belong to the same property? Actually, I see some issues here if we are taking deterministic logic.

What have philosophers said about this and how does philosophy deal with these issues?

  • The field of semantics addresses this issue by deciding which properties can be multi-valued (such as "color" for an object that has more than one color) and which are single-valued (like "size", or at least "length" or some specific measure of size)
    – user935
    Apr 27, 2018 at 19:32
  • @barrycarter, yes, and it's to some sense miraculous that people agree on language semantics themselves. They also are just notions. Like people can understand something they can't express as in the case of unrestricted grammars.
    – rus9384
    Apr 27, 2018 at 21:51

1 Answer 1


So, an object in the whole can't have two different values of the same property.

Not sure : can't X be a small elephant and a large mammal - small in comparison with the average elephant but large in comparison with other mammals ? Small and large - isn't this having different values of the same property, i.e. size ?

Properties such as large or small are relative to a description ('as an elephant') and a comparison. Colours such as green or blue are not comparative in this way. Y is blue - it is not blue in relation to or by comparison with another colour. It is blue or not blue (excluding cases where the particular shade of blue makes it hard to distinguish from violet or green on the visual colour spectrum).

But all colours are pseudo-properties in the sense of being relative to a perceiver. They are not properties of an object but visual sensations experienced by us when light of different wavelengths reflects from a surface and interacts with receptors in the retina of the eye. What I see as red, a colour-blind person may see as green, my cat may see as red, and a stomatopod as a colour I can't even imagine. But none of these entities perceives a colour property of the object, only a visual sensation purely explicable by the physics of light and the perceiver's visual apparatus.

  • The thing is that the same object possibly can have different colors for different persons. Take color blindness for example. But then we somehow agree on different properties.
    – rus9384
    Apr 27, 2018 at 9:23
  • @rus9384. Thanks for clarification. Answer revised. Anything wrong now ?
    – Geoffrey Thomas
    Apr 27, 2018 at 12:10
  • But then properties are not recognized, right? Or do fundamental properties even exist? In your example it's the wavelength that defines the color. But it's just our brain that maps wavelengths to colors. When we are dreaming there are colors but no wavelengths. There are other properties mapped to the color, but property "color" is the same.
    – rus9384
    Apr 27, 2018 at 12:21
  • Do we see colours in dreams or imagine that we are seeing them ? If the latter then they need not exist in dreams any more than the cat or dog I dream of exists. I dream that I see blue; it does not follow that there is blue that I dream. I suspect that even fundamental properties are relative to perception or at least to the human cognitive apparatus. But then I'm Kantian in epistemology and metaphysics. Another story !
    – Geoffrey Thomas
    Apr 27, 2018 at 12:54

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .