Shortly Comparing the Three Major Theories of Consciousness

In this post, I’ll be answering 4 questions that are explained in and drawn from Ned Block’s “Comparing the Major Theories of Consciousness” paper. I’ll be answering them shortly and as clearly as I can. I am currently taking his class at NYU, so hopefully this post explains them to a certain extent and gives an introduction to these theories.

For each question, I’m comparing
- Biological Theory
- Higher-Order Theory
- Global Workspace Theory

1. What is the (biological/higher-order/global workspace) theory of consciousness?

There are three theories of consciousness discussed in Ned Block’s “Comparing the Major Theories of Consciousness” paper. The biological theory sees consciousness as a biologic neural state of the brain. It is an electrochemical process and according to the theory, the perceptual content comes from the activation of perceptual areas in the brain. The theory doesn’t give one single account on what makes a content conscious, but there are several proposals. For example, proposals include, thalamocortical connectivity or activation of self-circuits. The higher-order theory claims that an experience is phenomenally conscious only if there is another state that is about that experience. So, an experience becomes conscious, for example, when one has a thought about that experience. For consciousness, this theory needs both representation of red in the visual system and a thought about that representation of red. This implies that there is an unconscious perception to start with. Third theory discussed is called global workspace theory. According to global workspace theory, there is a competition among the neural coalitions involving sensory areas and frontal/thinking areas in the brain. Sensory areas are in the outer layers in the imagery provided by the global workspace theory, and frontal/thinking areas towards the core of the circle. Strong neural connections compete with each other and the winning coalitions become conscious. Higher-order and global workspace theories are computational theories that doesn’t require biology to function. From the biological theory’s view, global workspace and higher-order theories are things consciousness does, but not what consciousness is. Also, the higher-order theory requires more intellect in the conscious being than others, and global workspace requires a more evolved brain for a being to be conscious. Consciousness might be something simpler, especially for those who are inclined to believe in consciousness in non-human beings. People who subscribe to either higher-order or global workspace theories object against biological view by saying that biological view has too much unnecessary detail.

image showing global workspace theory. stronger coalitions become conscious.

2. What is the significance of the explanatory gap?

Explanatory gap poses the question why a neural basis of an experience is the neural basis of that experience as opposed to another experience or no experience at all. It’s important because we don’t understand how or why an objective physical state (C fibers firing) gives rise to a subjective state (what it is like to feel pain). While it makes sense physiologically, it doesn’t help why pain feels the way pain feels. We don’t know how those two concepts refer to the same thing or can be the same thing. Chalmers calls the quest to close this gap, the “Hard Problem of Consciousness.” The main problem is that we have no idea how to close the gap, and we’re not even close to coming up with an idea, or to believe that at some point in time this problem can be resolved. The higher-order and global workspace theories don’t recognize that there is such gap. For the higher-order theory, the experience of red is phenomenally conscious when it’s accompanied by a higher-order thought about the representation of red. The problem in higher-order theory is how the higher-order thought that enables the first-order thought to be conscious can create consciousness when that thought itself isn’t conscious and needs a third-order thought to be conscious. But it’s not the real gap we’re trying to focus on. For the global workspace, the experience of red is conscious when the representation of red is globally broadcasted in the brain. The question for the global workspace theory is why a representation is conscious when it’s globally broadcasted, which is a different question than the explanatory gap. Both theories presupposes the specifics of their own theories to resolve the gap they gave, but neither acknowledges the explanatory gap and don’t see any more explanation necessary in neuroscientific terms. The biological theory acknowledges that there is such a gap and asks how consciousness can possibly be a biological property. The biological theory becomes more plausible for people who recognize that there is an explanatory gap, as the biological theory is the only one recognizing the gap out of the three theories.

3. What is the relation between consciousness and reports of consciousness?

Consciousness itself and report of the consciousness are two different things. Reporting consciousness means the being who is conscious is showing it to the outside world somehow that the being is conscious. For the higher-order theory, a state becomes conscious with the higher-order thought that is about that state, and this implies that that being can report (doesn’t have to be verbally) as it already has a thought about that state. The reporting comes with the higher-order thought, therefore with consciousness itself. The global workspace theory also links consciousness to reporting. According to the global workspace theory, what makes a representational content conscious is that content being present in the workspace and being present in the workspace itself causes reporting. In contrast, the biological theory doesn’t require reporting for a being to be conscious. The biological mechanism of consciousness and the biological mechanism of reporting doesn’t have to be linked, and reporting isn’t a necessary condition for consciousness. For the biological theory, consciousness can be completely unreportable.

4. How could a machine be conscious?

The higher-order thought theory suggests that if we can make a machine think, and if it can have representational contents and can think about those contents, then that machine is conscious, since that is the only requirement for consciousness according to the view. The global workspace theory is also sympathetic to the idea of machine consciousness as there is no biological aspect about the theory. Only broadcast of the content is necessary for consciousness to happen, and one can imagine such system in a machine made of non-biological materials. The biological theory doesn’t favor machine consciousness and requires the right kind of biology that supports electrochemical information transfer to have consciousness. It’s thought that a transfer of coding of information from electrical to chemical and back to electrical (which happens between neurons during synapses) is a necessary aspect of consciousness. It’s intuitive to think that the biology of the brain matters for consciousness to exist, since a person can only be sure of her own consciousness.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store