“Stated briefly, this is the view that physical objects are immediately and directly present to us in sense experience. Naive realism, may, however, take two forms, which will here be called simple naive realism and sophisticated naive realism.
Simple Naive Realism is the view that a physical object is directly present to us in each and every waking sense experience and that the proof of the object’s presence and nature lies in the individual sense experience itself.
Sophisticated naive realism holds first that physical objects are present to us directly only in some, not all, sense experiences, and second that evidence for the existence and nature of a physical object lies not in the single sense experience itself but rather in the manner in which the individual experience is related to other sense experiences.
In its sophisticated form, naive realism is less vulnerable.
For the sophisticated naive realist the external world is an aggregate of physical objects related to one another according to laws of nature. In order to determine whether any apparent physical object presented to us in sense experience is a genuine part of the external world, it is necessary and sufficient to determine whether its relationship to other bodies are those demanded by the laws of nature.
…As for the “error of sense” in waking experience, the sophisticated naive realist points out that unless we assumed the actual presence of at least some physical objects to our senses the expression would be completely meaningless. In speaking of a waking sense experience as misleading, we are merely affirming that because of a particular complex of circumstances and in accordance with certain laws of nature which are themselves knowable only by sense experience the object shows itself differently than it normally would. Consider again the half-submerged stick that appears bent. Why do we say that it is really straight? We do so because, first we can compare the initial visual observation with the visual and tactile sense experiences we have upon lifting the stick from the water and running our hand along it and because, second, these latter experiences together with other waking sense experiences give evidence for certain laws of nature from which the fact of a straight stick’s appearing bent when half-submerged in water can be deduced. It we did not assume the validity of these other sense experiences, we would have not the slightest reason to question validity of the first.
But how can the sophisticated naive realist reconcile his conviction regarding the direct presence of physical objects in waking experience with the belief that physical objects remain what they are despite changes in the circumstances of sensory or perceptual experience? If physical objects appear to us in their own nature, if they do not depend upon the position or physiological state of the observer, then why are we so often deceived? Square towers ought to appear square regardless of our distance from them…”
(Olson, A Short Introduction to Philosophy, 21-22)