Full Idea
A preconception and conception must precede every object of investigation, for how can anyone even investigate without some conception of the object of investigation?
Gist of Idea
How can you investigate without some preconception of your object?
Source
Sextus Empiricus (Against the Professors (six books) [c.180], 8.331a)
Book Reference
'The Hellenistic Philosophers:Vol.1 translations', ed/tr. Long,A. /Sedley,D. [CUP 1987], p.249
A Reaction
The Duhem-Quine thesis about the 'theory-ladenness of observation' is just a revival of some routine ancient scepticism. As well as a conceptual scheme to accommodate the observation, there must also be some motivation for the investigation.