No, not a thread about race!
How do I identify a tomato as being a red thing? It's certainly not a conscious process - tomatoes just look red! I have a 'colour sense' that tells me what colour objects are.
But the colour I see - that vivid, glowy sensation we learn to call the colour red - isn't a property of the tomato. The tomato is giving out billions of sub-atomic photons which have certain wavelengths and energies but they are not coloured red!
The colour I perceive bears a relation to the wavelengths of the photons, but wavelength and colour are only related - they are not the same thing. Someone with anomalous colour vision may well have a very diferent perception of a tomato from me, but we would agree on the wavelenghts of the photons involved - for that reason we often say colour is 'subjective' and wavelength is 'objective'.
So lets replace the tomato with a murder. I perceive it as immoral using my 'moral sense', and that happens as automatically and unthinkingly as when I perceived the tomato as being red. But - following the analogy - the murder is not objectively immoral just as the tomato was not objectively red.
But I perceived the tomato as red because its photons had certain objective qualities (eg more longer wavelength photons than short ones) - it wasn't completely arbitrary. Similarly there are objective aspects to a murder that - in an unconscious way - cause me to percieve a murder as something immoral.
I think its clear that just as people can be colour blind, people (such as psychopaths) have a faulty moral sense.