I would say that one of the most important philosophical conditions that arises out of the drama is how skewed individual perception truly is. There is no real, substantive, and overarching condition of "truth" that emerges at the end of the drama. Rather, there is the belief that human beings' biases preclude anything transcendent from being embraced in a full and legitimate manner. Each character believes that they are acting in a sense of totality, and in reality, they are not. Iago believes that his machinations and scheming represents a transcendent order whereby every single individual and occurrence can be calculated to his advantage. He is unable to do this with Emilia, and the ending proves his beliefs otherwise. Desdemona acts in concert with a belief of love, a transcendent notion that compels her to leave her life and merge her sense of being with Othello. This ends up becoming a step towards intense isolation and alienation, as Othello's descent causes her to be more cut off from others, leaving her perception to be far from transcendent. For Othello, I think he realizes, though he does not fully articulate it, that his state of being in the world is one where his own contingency spelled his own sense of doom. The emerging fragments of this resided in his own sense of doubt and insecurity that someone like him could be worthy of political power and personal happiness. For Othello, there is only this individual sense of perception that lies at his very core, precluding any other redemptive vision of totality from entering. These individual fragments of perceived truth lead him to embracing Iago's villainous ways, and doubting both himself, the people around him, and the woman he loves. In the end of the drama, the only valence with which to view reality seems to be that of individual perception, something that is skewed and incapable of providing any larger configuration of truth and meaning by which to effectively live one's life.