sense datum

In the end, we get a sense datum called an image.

The appearance is therefore a mental object, a sense datum.

It follows that the sense datum is not what is known but is an active way of knowing the world.

This distinction has gained much wider application, though Russell eventually rejected the idea of an intermediate sense datum.

In one sense this is ridiculous, since there is nothing red in a brain to act as a sense datum.

Moreover, the sense datum per se is an abstraction rather than a substantial entity, though sensing (conceived as an act) is very real.

This elliptical 'appearance' cannot be identical with the coin (for the coin is perfectly round), and is therefore a sense datum, which somehow represents the round coin to us.

This led to Carnap's Aufbau, an attempt to learn all knowledge from sense datum, using the notion of "remembered as similar" to bind these into clusters, which would eventually map into language.

When we see, he argued, we are not 'seeing' an image or sense datum in the mind: we are 'seeing' the world, albeit not in the direct fashion imagined by the naïve realist.