Full Idea
Relativity permits differences in the perceived secondary qualities not to imply genuine disagreement, whereas perceived differences of primary qualities imply that at least one perceiver is in error.
Gist of Idea
Relativity means differing secondary perceptions are not real disagreements
Source
Colin McGinn (Subjective View: sec qualities and indexicals [1983], 2)
Book Reference
McGinn,Colin: 'The Subjective View' [OUP 1983], p.10
A Reaction
An example of 'relativity' is colour blindness. Sounds good, but what of one perceiver seeing a square as square, and another seeing it obliquely as a parallelogram? The squareness then seems more like a theory than a perception.