Problem of truth and reality is age old in the field of philosophy as well as in the field of science. People very often confuse between ‘Truth’ and ‘Reality’ Most people think them to be one and the same, but there are differences. Whatever exist is real, reality and existence are interchangeable words. We can say truth, which is unchangeable and reality, which exist but change. False, which is not exist at all. People have suggested various taste to decide the (...) truth falsity of our description of reality. Some suggested Pragmatic theory and some other have suggested Coherence as a test of truth. Realism is also an ontological theory and has been probably the most ancient one. According to ancient man, real is that which perceived. Latter on, due to religious impact the knower became more important then the knowing object. Barkeley developed an extreme position that the objective material world does not exist at all. Dewey has developed the position called Instrumentalism. Halt, Perry, Marvin, Pitkin are the chief advocates of this position. Philosophers such as Darke, Lovejoy, Cellars, and Santayana held a position of Critical Realism. These people hold that mind does not see the object directly as they are but only through their representatives, as regards the object of knowledge is concerned, the Neo Realist are monist while Critical Realist are dualist. Indian rationalist philosopher Dr. D.D. Bandiste introduces a new concept of reality Radical Realism. He proved that knowledge change the knower not the object. to him every new knowledge make some change or other inthe knowing person. Epistemological position of john Dewey called instrumentalism. According to him knowledge is an instrument of action and a meaningful action is always of a problem-solving type. Every knowledge is an instrument to serve some need or other, neither is any knowledge final, nor is any truth final. Not only everything in the world is changing, their mutual relations also change. Knowledge is not a goal, but only a instrument to achieve this or that goal. In my paper I haves discussed various theories regarding whether knowledge change the object known. In this contest I have discussed varieties of realism, Idealismand so on, but importantly I have also discussed a new theory Radical Realism. (shrink)