One of my friends recently stated: "black is not a colour. It is the entire

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One of my friends recently stated: "black is not a colour. It is the entire absence of it, both physically and neurochemically." But can this be right? I understand what my friend is saying in that things appear black when they don't emit or reflect any photons of light, and that, as a result, there is nothing for the light sensitive cells in our eyes to detect. However, in everyday life we still view black as a colour, just as we do red or green. I should probably mention that my friend is a scientist and tends to take a strictly empirical and sometimes rather reductionist view of things. Consequently, I'm keen to get a broader perspective on this question from a philosopher. So, my question then is: is black a colour? Or, perhaps more accurately, does it even make sense for us not to consider black a colour?