Political parties are necessary condition for a democracy because :

(i) If every elected representative is independent, then no one will make promise for any major policy changes. The government may be formed but its utility will remain always uncertain. Non-party based Panchayat election also create same problems.
The rise of political parties is directly linked to the emergence of representative democracies.

(ii) Without political parties, democracies cannot exist.

(iii) If we do not have political parties-in such a situation every candidate in elections will be independent.

(iv) No one will be able to make any promises to the people about any major policy changes.

(v) The government may be formed but its utility will remain uncertain.

(vi) Elected representatives will be accountable to their constituency for what they do in their locality.

(vii) But no one will be responsible for how the country will run.

(viii) The role of opposition party in a democracy necessitates the existence of political parties.

(ix) As societies become large and complex they also need some agencies to gather different views on various issues and to present these to the government, that's why political parties are needed.