There is no 'external' proof that consciousness exists since any kind of behaviour can be reduced to certain triggers and actions, just as desires can appear to be nothing more than elaborately ramified goals. Certain behaviours might depend on qualia, say engaging in the social ritual of a wine tasting, but all of this is easily rationalised into physiological thresholds and response programs invoking a tree of sub-goals etc. But what distinguishes desires from goals is that the former have a certain psychological self-sabotaging quality and so replacing them with programs ends up as chasing consciousness via whimsical errors and inefficiencies. Who is it that would be interested in disproving consciousness if not a consciousness?