What term describes someone who attacks and seeks to overthrow popular ideas or institutions?

The term that describes someone who attacks and seeks to overthrow popular ideas or institutions is "iconoclast." An iconoclast challenges established beliefs or institutions, often criticizing and deconstructing widely accepted norms. This term derives from historical contexts where physical iconoclasm involved the destruction of religious images, but it has broadened to encompass a critical stance towards cultural or institutional dogmas.

While a radical may also advocate for significant change, it is typically in a more systemic way, voicing opposition to prevailing structures, rather than focusing directly on the ideas themselves. A revolutionary can be seen as someone who seeks to fundamentally change or overthrow a political system, but their focus is more on the broader political context rather than the assault on popular ideas per se. Vandal generally refers to the deliberate destruction of property and is not specifically tied to the critique of ideas or institutions.

Therefore, iconoclast precisely captures the essence of challenging and overthrowing popular ideas, making it the most fitting choice.