Philosophical discussions

We present a summary of the topics used in this book: Doubt is the characteristic of every human, everyone makes mistake in his perceptions and more or less understand this mistake. Descartes' philosophy begins with doubt and by passing the suspicion process reaches to ensure consistency. We tried to present a brief discussion about possibility and incumbency theorem, since Avicenna. has priority in this topic; his opinion is main center of our discussion. Pivotal item in Avicenna's theorem is existence of an external fact independent of human, which is the boundary between philosophy and sophistry. Whenever in psychology or even educative science, considering theoretical base and psychological events and its relation to body and its role in training of person's b more, we approach more to philosophy and whenever, we focus on biology and physiology, then we approach more on educative and psychology pure topics. In summary we can said that from Hegel's view, the history of the world is awareness of freedom and the philosophy of history is thoughtful evaluation of history.