Science (in an area like physics) works largely through abstract, quantitative representations. In philosophy of mind, there is a problem with ‘qualia’. Qualia are qualitative properties of subjective, experiential states. This is a problem because ‘qualities’ don’t seem reducible to quantity.
It is a straightforward matter to note that one can map from quantity to qualities. For example, one can understand (part of) the structure of human colour vision as correlating with 3 quantitative ‘dimensions’, A, B, and C. Each dimension holds a value from 0 to 255, say. The three numbers combined produce a location in an abstract, quantitative ‘space’.
This is how a colour is often represented in computer code – it is an abstract, quantified representation. More carefully: this is how coders represent the internal state of the computer, which combined with a causal chain involving a monitor produces experiences of certain sorts of colours in people under certain standard conditions. So, the three quantitative dimensions A, B, and C are usually called R, G, and B, which map to the phenomena of red, green, and blue colour experiences. By combining these three dimensions, one can produce a circle spectrum of regular human colours in a human who is looking at something like a monitor, because the monitor is made to receive inputs corresponding to the locations in the abstract quantitative space and produce certain optical phenomena as a result.
This is to say, subjective experience of colour has certain correlates in an abstract, quantitative ‘space’.
If scientific representation is taken to not be ‘relevantly transparent’ (contra someone like Daniel Dennett), then one can think of abstract, quantitative scientific representation as a kind of Pandora’s box, that upon being opened might allow subjective experience ‘into’ the scientific picture. More precisely: to allow subjective experience behind the abstract, quantitative picture that science ostensibly gives.
A seemingly coherent response to eliminativist materialists such as Dennett is: reality goes from subjective experience in certain cases (say) to abstract, quantatitive representations that occur in humans, so to speak. It is like the coder example, but in the other direction. That is, certain sorts of physical phenomena are subjective experiences which humans represent in an abstract, quantitative way.
If the above is right, though, then it also suggests that the problem of reducing qualia to quantity is confused: what we are doing in physics (say) isn’t reducing ‘things’ to other ‘things’, but rather introducing abstract quantitative symbols for things and then replacing one set of symbols for another in the case of reduction, where the nature of these symbols is useful for various reasons.