Why everything in Cosmos should be governed by Dharma- To understand this we must be able to first of all understand the definition of Dharma. Vedic culture looks at it in a very broad perspective and do not limit its meaning to the domain of a specific religion.
Principal power of coherence which enables the proper functioning of any system is called Dharma. We all are part of one or the other system governed by some intelligent laws. Whether it is the rotation of planet in our solar system or process of metabolism done by the microscopic cells in our bodies, all are following a system operated by some set of laws. These laws are governing the entire cosmos and are uniformly applicable on every system- like Digestive System, Ecological System, and Solar System…. These set of laws are also applicable on the karma (actions) done by human being in the form of Dharma, and to maintain the harmony in our lives, all should follow these set of infallible laws, then only a person will be able to live in peace and happiness. In fact the index of effectiveness is the extent of peace and happiness of a person.
The critical component in achieving the effectiveness is the ability to decide the right actions among all the available choices (alternatives). To choose the best among all these alternatives, a person must be able to evaluate them as per standard values so that he does not violate any of the laws and is adhering to his Dharma.
Dharma is the index of manifestation of excellence. Extent to which a family perform Dharma is the extent to which it succeeds in the manifestation of excellence. Dharma is important not only for the spiritual unfoldment of a person but also it is indispensable for acquiring societal prosperity or welfare. Hence all positive and negative phalas totally dependant on the extent of adherence of Dharma.
It is truly said in Bhagvad Gita:- Yato Dharma Tato Jaya – Means – where there is Dharma there is victory.