Does certainty distinguish knowledge from simple belief? What is knowledge? The definition of knowledge in Plato; a justified and true belief about a subject. Carrying this definition, knowledge must not only be justified by sufficient evidence, but it must always be true and believed to be true. The problem with this definition is then the low degree of certainty. What does it mean to have “enough evidence”? To what extent can we know the truth about something in the past, present and especially the future? Is believing irrational and will it not guide us to the truth? Does lack of certainty make something false? If we become critical of what we claim to know, it's easy to wonder if we know anything with certainty. However, even if we say something is false, does that make it useless? In order to analyze this problem, I will cite examples from the Natural and Human Sciences. But before that, I will define some key words which will be essential in my approach. I defined accepted as gaining approval from society and authority, rejected as being completely rejected or forgotten, today as the present and tomorrow the future. Now, considering the first problem raised by the statement: How correct is this statement in its description of the nature of science in general? I find this to be a rather pessimistic view of the nature of scientific theories. It may be true that the history of science shows that much of what we considered mature knowledge 100 years ago was to some extent false. We are currently using theories that did not exist at the time. If we view our current theories as correct - just as people 100 years ago viewed theirs, we can almost logically deduce that since the theories are different and our theories are middle of paper.... .. great truth. If we were to consider the extreme implication, there would be no pursuit of knowledge. If one adopts this perspective and remains pessimistic about it, their solution is no solution at all. In conclusion, I can see that the statement describes the reality of natural and human science, but it does little to show that science has generally been successful. undertake empirically and structurally, and how the knowledge we have today is useful and beneficial. From this essay we can see that there were times when knowledge was "discarded", but that does not mean that future investigations and expeditions will not result in knowledge. That knowledge is false does not necessarily mean that it improves nothing. As for the pessimism described by the statement, by elimination, false knowledge means one step closer to true knowledge..