[ExI] Red

[Ben Zaiboc]

On 29/06/2026 20:04, Adrian Tymes wrote:
> On Mon, Jun 29, 2026 at 6:54 AM Ben Zaiboc via extropy-chat
> <extropy-chat at lists.extropy.org> wrote:
>> Orange is also a bit of a puzzle. Is that a colour in itself, a variety of red, or a variety of yellow?
> Technically, each color is a wavelength of light - or, in practice,
> usually a cluster centered around a given wavelength.  Orange is such
> a cluster that is between what we call "red" and what we call "green".
>
> The subjective experience of perceiving the color orange is caused by
> stimulation of our eyes' red-sensing and green-sensing cones in a
> certain proportion.

This is a topic that can cause quite a bit of confusion, because the word 'colour' is used to refer to several different things. Having had a biological education, I think of the word mainly as referring to our internal perception - the qualia of seeing colours - which don't strictly correspond to the physical phenomena which many people call 'colour' - the wavelength of light reflected from a surface - and, as John has mentioned, a third factor is the properties of a surface which cause it to reflect and absorb certain wavelengths of light.

We have a colour called Magenta, but it doesn't correspond to any wavelength of light, or any band of wavelengths. It only exists in our minds (which makes it an interesting case, because it means that no physical object can have a 'colour property' of Magenta. I don't think that Brent has ever addressed that, although I've mentioned it before).

>
>
>>> ... the strawbery still has the red quality, which is different from the different type of light that is reflected.  i.e. the light isn't what has the red quality, it is the strawberry.
>>
>> I don't understand this at all. You seem to be saying that strawberries are red regardless of what they look like? If they reflected yellow light they'd still really be red? (I think that if you put a strawberry under a yellow lamp, without any red light shining on it, it would look yellow, but I haven't done this experiment).

> I think he's saying "a quality that is labelled 'red'", but his
> phrasing is incorrect.  By definition, the light has a "red" quality.
> Whatever quality the strawberry possesses that might also be labeled
> "red", it is only in relation to its ability to reflect light.  In
> other words, "red" has two distinct meanings: a property of the light
> reflected by the strawberry, and a property of the strawberry that
> allows it to reflect light that is red.  This second property exists
> whether or not the strawberry is currently reflecting any light: a
> "red" strawberry remains that sort of "red" even in pitch blackness.
>
> So what he appears to be trying to say is, this second form of "red"
> isn't possessed by the light itself.  But phrasing it as "the light
> isn't what has the red quality" incorrectly implies there is only one
> sort of quality that is labeled "red".
>
> I am not sure if he means that "redness" is this second type of
> quality - which, if so, would be utterly physically measurable and
> objective, making all his goings-on about subjective perception
> irrelevant - or if "redness" is the subjective experience of
> perceiving red, which would seem to be definitionally not a property
> of the strawberry itself, but instead of the perceiving entity.
>

Yes, that makes sense to me (with the caveat that there are three, not two, meanings of 'colour', as mentioned above, and I suspect that Brent is trying to introduce a fourth meaning!), but we need Brent to confirm or deny that this is what he means. I don't think it is.

-- 
Ben