Full Idea
At the end [of the three stages of objectivity] the secondary qualities drop out of our picture of the external world, and the underlyiing primary qualities such as shape, size, weight, and motion are thought of structurally.
Gist of Idea
We achieve objectivity by dropping secondary qualities, to focus on structural primary qualities
Source
Thomas Nagel (The View from Nowhere [1986], II)
Book Reference
Nagel,Thomas: 'The View from Nowhere' [OUP 1989], p.14
A Reaction
This is the orthodox view for realists about the external world, and I largely agree. The only problem I see is that secondary qualities contain information, such as the colour of rotting fruit - but then colour is not an essential feature of rot.
Related Idea
Idea 22354 Things cause perceptions, properties have other effects, hence we reach a 'view from nowhere' [Nagel, by Reiss/Sprenger]