Concept:
- The two reasons for power sharing are usually called the prudential reason and the moral reason.
- Separating them makes the answer clearer, because one looks at results and the other at rights.
Step 1: The prudential reason, based on results.
Sharing power lowers the chance of conflict between social groups. Where conflict builds up it turns into violence and political instability, so a shared arrangement protects the stability of the whole political order.
Belgium managed this successfully, while Sri Lanka suffered years of civil war after refusing to share power.
Step 2: Why majority rule alone is not enough.
A majority community can impose its will on others, and in the short term this may appear to work. Over time it damages the unity of the nation, and the tyranny of the majority ends by ruining the majority itself along with the minority.
Step 3: The moral reason, based on rights.
Democratic rule means sharing power with those who are affected by its exercise and who must live with its consequences. People have a right to be consulted about how they are governed.
Step 4: How the two reasons join.
A government becomes legitimate when citizens take part and thereby acquire a stake in the system. Such a government is both fairer in principle and more stable in practice.
Final Answer: Power sharing is necessary for a practical reason, that it prevents conflict and keeps the political order stable, and for a reason of principle, that people affected by a decision have the right to be consulted about it.