Part I: Truth and logic
Trying to be rational is placing restrictions on oneself. If I don’t want to be rational, I can be sometimes rational and sometimes irrational :D. Like playing a game without observing its rules, not being rational is easier. So why should anyone try to be rational? One observation is: we are more peaceful when we are rational. This is just an observation, not an answer. Moreover, it could be that it is the other way round: we are rational when we are peaceful :P.
Being rational is a way of accepting the reality. Reality is anything that is either verified through senses, or deduced from another reality(that is verified through senses). A rational argument is a link connecting two realities. Reality is interconnected within, through logical deductions. In other words, the set of realities is closed under deductions. Therefore, no untrue statements can be deduced starting from a true statement. Also, starting from an untrue premises, some deductions will be untrue. Some of them might be visibly absurd, and this way, deduction can be used to identify untrue statements. Thus, logic is used to keep our self within reality.
Therefore, the question really is, why should I restrict myself to reality?. Is it possible to live totally in an imagination, by believing it is true?. If not, what is the role of imagination? Also, why do we feel more peaceful when rational?
To answer these questions, we need to understand the origin and nature of all surreal objects that we can think of. I have broken my thoughts on this in to two other posts, due to its length :D.