Do you need a lens to take photos with a Argus C3 rangefinder camera?
An Argus C3 rangefinder requires a lens to take photos. Without a lens the light striking the film would be unfocused and would be one big blur with perhaps slight variations in brightness.
There were various lenses available for the C3 and they were interchangeable. One of the unique features of the C3 was the diaphragm shutter based in the body rather than in the lens as is the case with most diaphragm/iris types of shutters. If you can see the shutter diaphragm when you look at the front of the camera, then you need a lens.
If you manage to acquire a C3 camera and a compatible lens, this information at the Argus Collectors Group may help you in installing the lens.