Man's behavior- Rational or Belief-governed?

It has been said long back that,"Man is a rational animal". Rationality of human-beings is one feature that differentiates them from other animals. I have been thinking on this since some time. The conclusion that I have arrived up to is contrary. All the recent advancements of human race, though arousing amazement and awe, though exhibiting exceptional intellectual capacity of human race, have proved to be destructive for the environment, for other living beings and for the human race itself. Only man has cleared forests and established highly sophisticated settlements. Only man has deviced high speed vehicles and created terrible pollution on the earth, only man has invented and used highly destructive weapons. All these activities eventually prove to be destructive for others and itself. Hence, I feel that man is the most intelligent but the most irrational animal on the earth. Isn't it irrational to develop the concept and criteria of 'rationalism' yourself and then judge the behavior of other species from the same perspective and call yourself the best?

I observed my own behavior and behaviors of many others around me. I strongly feel, that human-beings do understand the self-developed concept of rationalism and logicallism quite well. They also try to show that their behavior is rational and logical. It overtly also seems to us that it is indeed rational. However, the real factor that governs human behavior is their beliefs. Human behavior and decisions are more belief-governed rather than logic-governed.

There is one strong belief in their sub-conscious minds like a trunk of the tree, diversifying itself into many stem-like beliefs about various circumstances and things that they face in life. By close examination of a person, one can easily figure out this trunk-belief supporting every belief that is behind each of their action.

So then what is the role of rationalism, rational thinking, rational behavior or logical behavior? Well, I "BELIEVE" that human-being very intelligently just uses logic and rationalism to justify their belief-governed acts. Of-course logic appeals to him. It may also play as one of many roots supporting his trunk-belief. Other roots may be the thoughts implanted since their childhood, their upbringing, the way others behaved with them, characters of the people that they regard highly etc.