Here's why:

* Continental-Continental Collision: When two continental plates collide, they are both relatively buoyant and resist subduction. Instead of one plate diving under the other, the immense pressure causes the landmasses to buckle, fold, and uplift, creating massive mountain ranges. Since there's no subduction, there's no magma generation, hence no volcanoes. The Himalayas, formed by the collision of the Indian and Eurasian plates, are a prime example of a non-volcanic mountain range.

* Other Convergent Boundaries:

* Oceanic-Continental Collision: This results in the denser oceanic plate subducting under the continental plate. The subduction process generates magma, leading to volcanic arcs along the continental margin.

* Oceanic-Oceanic Collision: Here, one oceanic plate subducts beneath the other, creating volcanic island arcs.

In summary, the absence of subduction in a continental-continental collision leads to the formation of non-volcanic mountain ranges.