Books on Amazon
Observational terms/Theoretical Terms/TT/Peacocke: Square: has to be experienced as such - an X-ray tube not - for scientists, the X-ray tube can be constructed entirely different, for lay persons not - different term. - Sensitivity for the property: necessary but not sufficient condition - "tomato-like" appearance or taste, no theory is required. - Square: a minimal theory of perspective is required. - There is nothing "square-like" what would correspond to "tomato-like". - Without square term no sensation of square, (not only no representation). - A perspectively distorted square is perceived as a square, but not perceived as distorted. (> Higher order). - Not so with "tomato-like": cannot be known as a tomato. (> counterfeit). - "Tomato-like" is not a criterion, otherwise tomato is an observation term. - Representation: tomato, not "tomato-like"
Theoretical Terms/Peacocke: every perception has representational content - e.g. "The particle collision produced the track": Problem: then the causality is in the representational content, then we have a priori knowledge. - Solution: observational terms and perception must be characterized simultaneously - applying only for observed content (not for theoretical terms). - The experience must also be made if the object is not covered by these theoretical terms.
Particle pair/observation terms/theoretical terms/Peacocke: here, not the same conditions apply for changing angle, etc. - one can imagine here that the track of the particle pair in the cloud chamber does not result from a particle collision. - Unlike e.g. square - but that does not mean that squareness would be a secondary quality in the sense of power to evoke a feeling.
Theoretical Term: when a perceived object falls below a theoretical concept, then there must be a level of representational content on which the experience could be made, even if the object does not fall under this theoretical term - just thereby "track caused by a particle collision" turns into a theoretical term.
Chr. R. Peacocke
Sense and Content Oxford 1983