Albert Einstein on Concept

“All concepts, even those which are closest to experience, are from the point of view of logic freely chosen conventions.”

“Concepts have meaning only if we can point to objects to which they refer and to rules by which they are assigned to these objects.”

“The aim of science is... a comprehension, as complete as possible, of the connection between the sense experiences in their totality, and... the accomplishment of this aim by the use of the minimum of primary concepts and relations.”

“Concepts can only acquire content when they are connected, however indirectly, with sensible experience. But no logical investigation can reveal this connection; it can only be experienced. ...this connection ...determines the cognitive value of systems of concepts.”

“The belief in an external world independent of the percipient subject is the foundation of all science. But since our sense-perceptions inform us only indirectly of this external world, or Physical Reality, it is only by speculation that it can become comprehensible to us. From this it follows that our conceptions of Physical Reality can never be definitive; we must always be ready to alter them, that is, [to alter] the axiomatic basis of physics, in order to take account of the facts of perception with the greatest possible logical completeness.”

“I believe that the first step in the setting of a "real external world" is the formation of the concept of bodily objects... Out of the multitude of our sense experiences we take, mentally and arbitrarily, certain repeatedly occurring complexes of sense impressions... and we correlate to them a concept—the concept of a bodily object. Considered logically, this concept is not identical with the totality of sense impressions referred to; but it is a free creation of the human (or animal) mind. ...by means of such concepts and mental relations between them, we are able to orient ourselves in the labyrinth of sense impressions. These notions and relations, although free mental creations, appear to us stronger and more unalterable than the individual sense experience itself, the character of which... is never completely guaranteed.”

“Concepts that have proven useful in ordering things easily achieve such an authority over us that we forget their earthly origins and accept them as unalterable givens. Thus they come to be stamped as “necessities of thought,” “a priori givens,” etc. The path of scientific advance is often made impassable for a long time through such errors. For that reason, it is by no means an idle game if we become practiced in analyzing the long commonplace concepts and exhibiting those circumstances upon which their justification and usefulness depend, how they have grown up, individually, out of the givens of experience. By this means, their all-too-great authority will be broken. They will be removed if they cannot be properly legitimated, corrected if their correlation with given things be far too superfluous, replaced by others if a new system can be established that we prefer for whatever reason.”