Full Idea
The sensum-theory seems to me less probable than a causal theory of perception, which regards sensuous experience as not being apprehension at all, but a set of mental events produced by external bodies on our bodies and minds.
Gist of Idea
I prefer the causal theory to sense data, because sensations are events, not apprehensions
Source
W. David Ross (The Right and the Good [1930], §IV)
Book Reference
Ross,W.David: 'The Right and the Good' [OUP 1930], p.127
A Reaction
The point is that there is no third item between the object and the mind, which has to be 'apprehended'. Sense-data give a good account of delusions (where we apprehend the 'data', but not the real object). I think I agree with Ross.