Perceptual experiences are directly accessible to the observer, but observation statements which form the basis of the inductive ``proof'' are public entities. Such entities are formulated in a public language, involving theories of various degrees of sophistication. Theory of some kind must precede all observation statements, and thus observation statements are as fallible as the theories that form their predicates.
Example 1:
Reaction time (RT) is a function of the level of arousal
Note: The fact that the association is measured at all implies some theoretical predicate, however imprecise. Further it implies that the level of arousal and RT can be defined and measured}
Observation statements are always made in the language of some theory and will be as precise as the theoretical or conceptual framework that they utilise is precise. In other words, precise, clearly formulated theories are a pre-requisite for precise observation statements. In this sense theories precede observation. This runs counter to the logical empiricist's thesis. Thus
``Observation statements are as fallible as the theories that they presuppose and therefore do not constitute a completely secure basis on which to build scientific laws and theories''
Example 2:
Early experimenters in the field of electrostatics reported observations of electrified rods becoming sticky, as evidenced by small pieces of paper sticking to them, and of the rebounding of one electrified body from another.
Comment: From a modern perspective these observation reports were mistaken. The false conceptions that facilitated these observations would now be replaced by the notions of attractive and repulsive forces acting at a distance. This would lead to quite different observation reports.