no, by definition radicalism can be extremism.
No. Extremism and radicalism are two different political status.
Radicalism is a spectra of political vision. (for exemple, Macron is a radical liberal). Extremism is set on violence.
Radicalism is related to the political vision it fights and the sociological context of the struggle
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Extremism is not related to the political vision it fight, its the extrem status and nature of the political vision.
Example with FEMINISM:
- Radicality (in our current world) is saying that we must end patriarchy by changing the entire system.
- Extremism would be believing that only violent actions (like the sufragettes) can creates changes for women.
Example with CAPITALISM:
- Radicality (in our current world) is saying that capitalism is one of the disease of the human civilization
- Extremism would be believing that only violent actions or state coup are the only way to take down capitalism
Example with MERITOCRACY:
- Radicality (in our current world) is saying that Meritocracy is what helps Capitalism strive and keep people in situation of inequalities.
- Extremism would be believing that only by killing the rich we can create a equal distribution of wealth.
What you must understand is that Radicality is related to the sociological context of the struggle. Meaning that in a different context, lets say a more social environment, a specific radical statement like "meritocracy is a problem and we must end it" will not be as radical.
Radicality evolves where extremism remains extremism.
The reason why you think I have a very different set of definition, is because you live in a world where definitions are set by those in power. And right now, those in power are radical liberal, capitalist who are also rich pro status co wannabe progressists who try to appear as reasonable people.
The notion of Militantism and clear radicalism goes against their program and their existence. This is why we must use it and not fall into their trap by saying that radicality = extremism