In many works of ancient and contemporary logicians, there is no clear distinction between logic and epistemology, and this causes them to mix up the rules of one with the other. In this paper, I will deal with Gholamreza Zakyani and specially Mortaza Hajhosseini, among contemporary thinkers in Iran. Gholamreza Zakyani claims that contradictory propositions do not yield any results. In this article, we show that this claim is actually a confusion between logic and epistemology. On the other hand, Mortaza Hajhosseini has developed non-standard logical systems based on specific philosophical foundations in the second edition of his book Two Non-Classical Logic Systems, A New Outlook on Elements of Logic. In our opinion, he imposes epistemic principles on logic. Some of the explicit or implicit theoretical foundations of his logical systems are: 1. Contradiction only entails contradiction. 2. A logical theorem only comes from a logical theorem. 3. Knowledge cannot be had of a contradiction. 4. Knowledge of theorems is independent of knowledge of other propositions. 5. Logical theorems are the most superior propositions and since the result depends on the inferior premises, a logical theorem cannot be inferred from other propositions. 4. The contradiction is the most inferior proposition and since the result depends on the inferior premises, contradictory premises can yield only a contradictory result.