If the brain can give rise to consciousness, then any matter can give rise to consciousness, because for any material system, there is some frame of reference, however arbitrary and complex and twisted (and all frames of reference are ultimately arbitrary), under which the physical system appears to behave exactly as a brain does, because all positions and motions of atomic and subatomic particles are relative to other positions and motions.

All it takes is a possible frame of reference by which the particles are arranged in and behave in such a way that they give rise to consciousness to make the system conscious, as even the natural frame of reference that observes a brain behaving with the dynamic that it normally seems to (say, the frame of reference of a scientist studying a brain with some scientific apparatus) is arbitrary, unless you want to say that a conscious being has to occupy that frame of reference, but then an argument that consciousness is an emergent property of material would be an infinite regress.

That is, if you assume that our frame of reference is necessarily the one by which a conscious dynamic must operate, then you are assuming that a consciousness must exist having that reference frame of observation, and that consciousness must in turn have a consciousness that exists to validate the frame of reference by which its internal dynamics render a phenomenology, ad infinitum.

(It cannot be the consciousness in question that validates its own reference frame, because that would be to cause oneself to exist, and also we do not observe the submolecular motion involved in our own brains, so it must be another’s consciousness that validates the reference frame. (Granted, the conscious entities (humans) that comprise the reference frame in which other conscious humans are normally recognized don’t observe consciousness by observing submolecular action either, but by observing the physical dynamic on a more macroscopic scale—looking at facial expression and body language, listening to words, etc. However, reductionist theory does not say that consciousness is made up of the dynamic of observable motor command, which is why I appeal to a dynamic of subatomic particles wrt what supposedly composes consciousness.))

Of course, one could say that, in some equally strangely arranged frame of reference, a stereo system is a can opener. And yes, this would have little meaning because the stereo system could be anything from any arbitrarily arranged, complicated and convoluted frame of reference, and we, in our frame of reference, cannot possibly use it as a can opener, or garage door opener, or whatever. However, when I say that this item can (according to some reference frame) act as a brain, I am saying (according to the above argument, when we suppose that consciousness is an emergent property of the brain) that there is a phenomenology—a self; an experiencing entity—hidden in that stereo system, or actually, a countless number of phenomenologies, and they don’t need relative observers to feel, know, desire, perceive, etc. (whereas, e.g., a fork can be defined completely on a functionalistic basis).

Conclusion: either consciousness is everywhere, or consciousness is not a function of the brain and, more generally, cannot be reduced to any system of parts. Also, if consciousness can be reduced (and is everywhere), then every conscious system simultaneously has every possible phenomenology/inner experience.

Admittedly, I don’t know what the implications would be in regard to a non-reductionistic theory of mind being a function of the brain.