the dialectic thinking

Cicero studied his opponent's case with equal effort or even greater effort. Mill was trained by his father to argue both sides of every question.
I have heard the word "Dialectic" since I was in middle school. It was not until recently that I found its importance in writing as well as in daily life. When I write a critique, the dialectic approach is required in considering whether the article contains important counterargument and hence is balanced or not. In daily life, equipping with dialectic thinking appears to be more important. Today, I apply for a visa to US in order to make a trip to visit my aunt and uncle after my exchange semester is over. Though my uncle, aunt and I had fully prepared for it thinking that the material is convincing enough, my application is denial. The reason, from the consular officer, is "my tie to the Singapore is not strong", and he also gives advice that I'd better apply in China. The case itself is not interesting. What matters here is the feeling of confidence before I applied the visa. Making such argument, I studied my case carefully, but not study the opposite—in what situation that I will be denied for a visa. So there should be no reason for me to be so confident before applying.
Studying the opposite not only matters in daily argument; it is also crucial in self- examination. I am the habitual tendency to consider only the positive side of a case, which may contribute to my optimistic character, and which also prevent me from seeing the fault. Back in home university, I received much more praise than criticism. Praise lead to my pride and sometimes arrogance. I need criticism to see the true self. If such criticism is not able to reach me from the out, I will make myself its source.