Should we prohibit parties recognized as extremists?

Context

And if the second German political force in the last elections, the alternative for Germany ( Alternative für deutschland, AFD) became illegal? The Federal Office for the Protection of the Constitution opens the way to a possible constitutional ban. The organization, after three years of investigation, estimates that AFD, 152 seats in the Bundestag (Parliament), “is not compatible with the fundamental democratic order”. The party seized the administrative court, while thousands of Germans demonstrate to claim its exclusion. Should we prohibit movements when they consider that they threaten democracy? Two experts respond.