The principle of non-contradiction is, according to many scholars, the most central principle in human knowledge, whose negation would lead to the closure of sciences. Since long ago, some paradoxes have been put forward in refutation of this principle. Resolving those paradoxes is necessary for defending the validity of human knowledge and removing the sophistic doubts. In the present article, we have attempted to resolve, through the analysis of the reality of truth, some important paradoxes and show that these paradoxes do not negate the abovementioned principle. Regarding the Liar Paradox, while offering a solution for it, we have argued that the paradox lacks the necessary conditions to be called “true” or “false”. We have also showed that how Grelling’s paradox is resolved by considering contradiction of predicates. The paradoxes of Russell and Counter are indeed resulted from the confusion between “universal and general” as well as “validity and truth”. Thus, none of the paradoxes negate the principle of non-contradiction.