A1 Consciousness. Consciousness is the most important and most troubled knowledge area. It is addressed below. The initial focus is on interoception.
A2 Mental faculties
A2.1 Interoception. Hunger, thirst and other sensory modalities by which a person is directly aware of an internal state of the body.
A2.2 Awareness. Awareness is exemplified by wakefulness as contrasted to dreamless sleep or comatose condition. Awareness is the necessary background condition to enable experiencing particular foreground events.
A2.3 Cognitive knowledge. Cognitive mechanisms are innate. They involve generalization and conceptualization of knowledge.
A2.4 Exteroception. Vision and other sensory modalities by which the external world is made observable
A2.5 The esthetic sense. The positive affect resulting from innate pattern recognition.
B1 Life and thermodynamics. Except in absolute zero temperature macroscopic physical systems move from less probable to more probable states. Organisms, while alive, defer that outcome by using ingested energy to drive negative feedback mechanisms that maintain each vital variable vital (e.g. glucose) within its narrow set-points, which are far from thermodynamic equilibrium.
B2 Homeostasis. Homeostasis is a state where each vital variable is within its set-points. Like health, homeostasis is a goal-state, while the negative feedback mechanisms are goal-oriented. Homeostasis characterizes metabolic life.
C. The function of interoception
C1 Normal departure from homeostasis. Depletion of glucose level is an example of departure from homeostasis that requires associated mechanisms for its restoration. In primates and some mammals, interoceptive subjective state is elicited prompting a voluntary behavior aimed at restoring homeostasis.
C2 Stages of the interoceptive response sequence
C2.1 Initiation. Restoration of homeostasis requires behavioral response.An interoceptive sensation with a negative affect, such as hunger or thirst is elicited.
C2.2 Cognition. Interoception triggers cognition. Cognition selects one of possible alternative actions and triggers the brain motor areas.
C2.3 Behavior. The motor brain triggers behavior intended to secure needed satisfaction.
C2.4 Need satisfaction. Need satisfaction (e.g. eating or drinking) is associated with pleasure. It is then followed by a sense of satiety.
C2.5 Return to non-conscious homeostatic regulation. The sense of satiety is brief. Then automatic non-conscious homeostatic regulation resumes.
D. Some epistemological aspects of interoception
D1 Interoceptive sensations are innate and private. The newborn possesses interoceptive capacities prior to post-natal experience: they are innate. An interoceptive sensation is confined to the single individual who experiences it directly. Thus, interoceptive sensation is private, and thus subjective.
D2 Non-physicality. The physical are events locatable in time and space and are publicly observable. Interoceptive sensations are private and therefore do not satisfy the physicality criterion.
D3 Interoception manifests the causal efficacy of subjective states. The fine elicitation and withdrawal of interoceptive subjective states indicates that evolution takes subjective states to be causally efficacious.
D4 Interoception is goal-oriented. Interoception is an extension of the goal-oriented homeostatic mechanisms.
D5 Universality. While some mental attributes differ among individuals, interoceptive sensations are universal.
E. Human nature
E1 Innate commonalities. Innate interoceptive commonalities constitute the core of human nature.
E2 Human conduct. Innate commonalities of human nature is the ground for universals of human conduct.
F. Interoception and epistemology
We find that interoception is innate, subjective, universal, goal-oriented and causally efficacious. Our 300-year-old theory of knowledge is outdated: it denies the existence of any of the above attributes of interoception.
G. A claim
To my knowledge, the above is the first proof for the existence of commonalities of human nature and its basis for universals of human conduct.