A person with strong convictions or a person who favours a change from the present social, political and economic conditions is generally called as radical.In the modern days a person with radical views may even be called as extremist.
During the French revolution those who abhorred the anarchy prevailing in the French King’s rule and who favoured a change, were called as radicals and were even persecuted mercilessly.The whole French Revolution was led by those radicals, under different nomenclature in various phases.
In India, after the formation of the Indian National Congress in 1885, Congress was divided into two, and the people who had mild views as against the then British Colonial rule were led by Gopalakrishna Gokale and those people with radical views were led by Bala Gangadhara Tilakar.This split in the Congress occurred in 1907 in the Surat Congress.
The leaders who had radical political views wanted to see a volte face in the political set up of India.They wanted complete independance from the British colonial Rule.
Finally, it was the radical group led by Mahatma Gandhi that won independance for India on August 15, 1947, with a minimum of violence.Of course,various extraneous factors, such as the outbreak of the Second World War in 1939 that ended in 1945, formation of the United Nations Organisations in 1945 and the Change of political ledership in England overthrowing Winston Churchill as the Prime Minister of England,etc facilitated the liberation of various countries such as India, Sri Lanka, Pakistan and many other countries from the colonial rule of England.
So radicals had always played a significant role in changing the destiny of many countries in the world.