Aristotle propounded the realist propaganda. It encapsulated the belief that any form of knowledge that we wished to gain pertaining to any matter can be extracted from simple observations of our surroundings. These surroundings encompass the reality, and observing this reality and subjecting this observation to common sense could help establish the degree of factuality of the subject matter at hand which we wish to study.
The world continued to practice the theory of realism until scientific experiments with subatomic particles shook the basic foundations of the realist theory of Aristotle. Particles at the subatomic particles portrayed a random behavior. This random behavior made it hard to propound any form of postulates from which conclusions could be derived. The basic flaw that was seen in the realist theory was that when particles at the subatomic levels behave randomly, then is it even justified to base conclusions on an empirical level.
The contrasting view to the realist theory, namely “idealism”, proposes that knowledge about anything cannot be determined with any form of direct connection with the reality. Whatsoever our senses interpret about the subject matter, it becomes the reality for us. In other words, everyone who intends to gain insight into any subject matter will have a different understanding of the matter since their sensual understanding of the matter may vary from person to person. The debate between the two still perplexes the scientific community at large.