Dualistic theories of consciousness typically deny that it can be accounted for in the current terms of the natural sciences. Traditional dualists may argue that the reduction of consciousness to physically describable mechanisms is impossible on any concept of the physical.  Others may hold that consciousness is an as-yet-undescribed fundamental constituent of the physical universe, not reducible to any known physical principles. Such accounts of consciousness (with the possible exception of those based in anthropocentric theology) provide no principled reasons, however, for doubting that animals are conscious.