The basic rationale of Tai Chi Chuan is unique amongst martial arts and sparring systems. 

I believe that it is the realization of Lao Zi and Zhuang Zi’s thought in a martial arts context.  

Politically, it is expressed as Huang Lao’s craft of non-action.  In Tai Chi Chuan the principle is the same: by focusing on being spontaneous, elastic, sinking and unfolding in a relaxed manner, the person maintains his or her own centre of gravity while generating the conditions which offset the opponent’s equilibrium.

However, actively attacking the opponent does not necessarily unbalance him.  Instead, take advance of the inevitable loss the balance accompanying the opponent’s attack and add a slight push to create an even greater loss of equilibrium. 

Therefore, Tai Chi Chuan emphasizes the sayings: “Stillness overcomes movement… Four ounces can move 1000 pounds… Defeat the opponent by counter attack. ”  Tai Chi Chuan does not advocate brute force. 

The opponent is the source of energy; merely change the direction of his force. The opponent defeats himself, toppled by this own force. If the opponent can consistently maintain his own centre of gravity, perhaps by not attacking at all, then he may be spared defeat. Never initiate the attack. 

Everything in the universe is forever changing. Tai Chi Chuan may appear slow and unhurried to an observer, but the movements flow together continuously, without pause. Architecturally speaking, a curved line can support much more weight than a straight line. Likewise, in Tai Chi Chuan, speed is not the prime objective. Balance and stability are more important. 

Push Hands practice is extremely important because it requires an acute ability to sense and become aware of mistakes and flaws in the opponent’s moves. If he is making no mistakes, then create an opportunity for them to occur.

It is imperative that your own moves be executed flawlessly. As long as the opponent intends to knock me over or attack me, then his weakness will be exposed. “Preserve gains and maintains stability. Modesty brings gains, haughtiness yields loss.” This is an essential aspect of the political and personal philosophy of Chinese people. It is much more important to be spared defeated than to defeat the other. As long as I myself am not defeated, it does not really matter whether my opponent loses. If he does not handle himself well, he will eventually be defeated. If he does handle himself well, that is also fine. 

Dating back to the founder, Taoist monk Chang San Feng, Tai Chi Chuan is rooted in Taoist philosophy. Lao Tzu emphasized that in order to obtain, one must first give. The truly powerful does not make a fierce, dramatic entrance; he saves his strength, letting the opponent exhaust his energy. Then, when the opportunity arises, he takes advantage of the situation, choosing the outcome.
The study of Tai Chi Chuan is not only for improving combat skills, but for developing the mind. This is more than simply “wit defeating force.” The highest lever of Tai Chi Chuan seeks even more than development of mind. It aims to cultivate a more moderate and peaceful way of being. Rather than using softness to overcome hardness, the highest lever refrains from attempting to overcome at all. As long as the mind holds the intention of “defeating the opponent”, then it is impossible to reach the higher levers of Tai Chi Chuan. In fact, as long as there exists a desire to “reach the higher levers”，then they will remain unattainable.