Is science a belief?

[Trinoc]

Four effective internal primary colours, red, yellow, green and blue.
Other colours (cyan, magenta, etc) are not hard to imagine as blends of the first four, but yellow doesn't feel at all like a blend of red and green.
If anything, in terms of 'feel', green is closer to being a blend of blue and yellow.

I see what you mean, but I'm not convinced. There are only three sensors (except in a few women with tetrachromacy due to having one Daltonism gene). If you include the sensations caused by combinations of these then you have to regard the spectrum as a continuum, and yellow has no more special place than anything else, except perhaps for being the colour to which the eye is most sensitive.

Violet and magenta are oddities, since violet is off the scale covered by the cones and yet can still be perceived by virtue of the lower response from green and red cones, and magenta has no corresponding single wavelength since it involves stimulation of read and blue cones but reduced stimulation of green. Interesting that the two colours which rely on lower than normal stimulation of the green cone produce similar colour sensations.

[Trinoc]

According to the New Scientist, some people have four types of colour receptors - the "tetrachromats". They are always female, as it is associated with the X chromosomes. They therefore see variation in what most people would regard as one shade of a colour.

This was posted while I was typing my reply ...

Tetrachromats are rare exceptions, though.

[tolman]

Leaving aside the unquestioned ability of red/green/blue to act as external primary colours, I'd suggest that things like the widespread use of red, green, blue and yellow as the colours to use for a huge range of baby toys (bricks, etc) does rather reflect an implicit acceptance of those four colours as at least somehow internally privileged.

Whatever the number of different receptor classes in the retina, there's no reason at all why the internal colour space must mirror that of the sensors.

Processing the input signals by means of colour differences can easily lead to internal representations which don't have any obvious mapping to the receptors.
Indeed, (at least for people who see them as primaries) the internal 'red' and 'green' are fairly far removed from the signals from the 'medium' and 'long' receptors, and must themselves have been generated from some significant processing.
Generating difference signals from 3 types of input could lead fairly naturally to having a 2-dimensional space for representing hue and saturation, with results being somewhere on a graph with, for example, red-vs-green and blue-vs-yellow axes.

[Trinoc]

Here is your 2D graph - variations on it are used in all video, printing and dying industries. The axes are not red-green and blue-yellow, though.

Some other useful info here.

[Matt]

Green is considered a primary colour when combining light. Yellow is not
Yellow is considered a primary colour when filtering light, for example with pigments - typically paint mixing. in that paradigm Green is not considered primary.

[Tim the Mage]

My uncle was totally colour blind. I always assumed that it would be impossible to describe colour to him yet he worked in an environment (a pharmaceuticals research establishment) where I suspect an understanding of colour is required.

Having strayed from the thread I've found it quite enlightening - thanks.

[Tony Williams]

My uncle was totally colour blind. I always assumed that it would be impossible to describe colour to him yet he worked in an environment (a pharmaceuticals research establishment) where I suspect an understanding of colour is required.

Well, if you think about black-and-white photographs, you can make a lot of fine distinctions with different shades of grey.

[Mongrel]

My uncle was totally colour blind. I always assumed that it would be impossible to describe colour to him yet he worked in an environment (a pharmaceuticals research establishment) where I suspect an understanding of colour is required.

It's be interesting to hear his side of things, that's for certain.

What I suspect though is that he worked harder to train himself so that his colour blindness wasn't a hindrance. For example, from a purely H&S perspective everything should be clearly labelled anyway - he just has to read the labels or even look at the shape of the container (if there was a difference).

Another example is a friend of mine who suffers from Red-Green colour blindness, he doesn't have to know what the colours are in the traffic light just that the top one is stop and the bottom one is go (he's also handy to have around for testing web sites in that regard as well )

[Pebble]

Meanwhile back to the topic at hand.

If I understand the arguments to date I would summarise:

Science is a method not a belief. At it's heart is empiricism and a quest to minimise assumptions.

The philosophers view is that it is impossible to get rid of all assumptions (one has to assume that you exist to do the studies in the first place) and concludes that as one cannot get rid of all assumptions, then the whole of science is a logical fallacy.

Any advance or corrections?

[Tony Williams]

The philosophers view is that it is impossible to get rid of all assumptions (one has to assume that you exist to do the studies in the first place) and concludes that as one cannot get rid of all assumptions, then the whole of science is a logical fallacy.

Which just shows that too much thinking about a subject can result in you disappearing up your own fundamental orifice

All of our understanding of existence involves an assumption we do actually exist. So is existence a logical fallacy?

[Croydon Bob]

All of our understanding of existence involves an assumption we do actually exist. So is existence a logical fallacy?

Like most skeptics (including you probably) I don't find these debates very useful. I grew out of them at the same time that I stopped dropping acid in my early twenties.

At the end of the day we all think that we exist, and we operate on an assumption that we exist and that "reality" is real. When nutters claim that they don't think any such thing and believe that this existence is all a dream or some similar nonsense, they are lying. Otherwise why do they bother to look before crossing the road, go to the doctor when ill, etc?

If everyone in history had started from a position of wondering about the existence of existence then humanity wouldn't even have the wheel let alone anything else that helps make our lives so comfortable.

Or to quote the philosopher, and Skeptics in the Pub founder, Dr. Scott Campbell: "That's bollocks, it's just philosophy!"

[Mulder]

Why do people 'drop' acid instead of just taking it? Does drop have some specific meaning here. I should say I know nothing of drug culture.

[farmersboy]

Why do people 'drop' acid instead of just taking it? Does drop have some specific meaning here. I should say I know nothing of drug culture.

Because it was originally available in liquid form, not pills.

Apparently.

[Trinoc]

Because it was originally available in liquid form, not pills.

So why doesn't one "drop" a cup of tea or a pint of beer (unless very clumsy, that is)?

[tolman]

Not only was it a liquid, but a potent one.

Often, it was packaged as drops soaked into paper in a [possibly patterned] grid, which was then dried and cut into small pieces, so people were actually taking one drop per piece.

At least in the UK, the existing term 'Acid Drops' might have provided at least some small amount of resonance, but I'm not sure if that had any meaning in the USA?