I would say that you need a medium in which to execute your art, otherwise it's just your imagination. To me it's not art until it's outside your head and reified.
Originally Posted by Cold
And you need some level of skill to work in any medium, but the bar can be pretty low. A 5-year-old's scrawl is sufficient craft-skill to execute literature, the art is in the emotions etc evoked by the words, not the physical form of the words. Or if you want to do photography, you need to be able to compose and push a button, optionally make a selection of aperture/speed - again, I could teach that to a 5 year old. What matters is your composition, choice of light and how it affects the viewer - all the crap with phenidone and thiosulfate or photoshop and inkjet is just craft choices and can all be outsourced if you want without reducing the art that you reified (made real, fixed into a medium) when you opened the shutter - just like HCB outsourced all the craft of print-making.
Sure there are some correlations between people with powerful craft skills and people with good artistic vision but that's only because they practiced them concurrently. There a many more people with one and not the other, especially people with craft and no art. Citation: 99.9% of the photos people put on the internet. Conversely, I've seen wonderful art made with shitty cellphone cameras and while they might look better shot on LF Velvia, that doesn't reduce the artistic value of the images those people made where the only craft skill involved was "push the button".