Implications of Substrate Independence

Physicalism is a metaphysical theory that claims that minds and consciousness are products of physical brains. In other words, minds are the result of ultimately mechanical structures and interactions. Minds are conscious computers.

This leads to an idea called substrate independence (or substrate neutrality) which asserts that minds can be produced by anything simulating a brain regardless of the materials used. Computer simulations have become the most popular example of this idea, particularly in the field of artificial intelligence. Prominent philosophers such as Daniel Dennett support substrate independence and the corresponding ability for conscious machines.


One of the more intriguing applications of substrate independence is a mind composed of other minds, or what I call a macro-mind. Imagine that people are given jobs that simulate brain neurons. If together they simulate a brain, then according to substrate independence, they’re creating a mind that is present somehow among the group yet independent of the minds of the individuals.

Minds have senses and feelings. Minds have thoughts and free will. Minds have a sense of self. A macro-mind would be something capable of influencing itself and its environment that was greater than any individual mind within it.

This raises an important question: What if this is already happening? What if we’re already acting like neurons in a brain, and our technology is facilitating and thus waking up this larger mind?

What’s the least complex structure and set of behaviors needed to form a mind? Maybe there are hierarchies and layers. Institutions, businesses, governments, cultures, industries, nations—could these organizations and groups literally have minds of their own? Minds with their own personalities, beliefs, and agendas?

It sounds bizarre, but it’s entirely plausible if substrate independence is true.


Equally bizarre is the idea that what we call our unconscious mind could itself be a conscious mind—one that we only have partial access to. Given substrate independence, having more than one mind in a brain is possible. If the brain can create consciousness in one part, why not another? The fact that people can retain a mind after a hemispherectomy is evidence that only half a brain is sufficient to produce a conscious mind.

Suggesting the possibility of micro-minds, as I call them, is a condition called alien hand syndrome, where an entire appendage seems to have a mind of its own.

Dissociative identity disorder (DID)—formerly known as multiple personality disorder in the US—is another example. The alter egos (or alters) of people with DID each have all the qualities of being independent minds. These alters can have different personalities, memories, behaviors, knowledge, speech patterns, handwriting, moods, food preferences, and so forth.

Another example is patients with a “split brain.” These are people whose corpus callosum is severed, causing an inability for the left and right cerebral hemispheres to communicate with each other. There are numerous cases of split-brain patients displaying conflicts resembling differences of interests between two minds.

Identifying minds

If these micro-minds exist, how might we test to see if macro-minds exist as well?

Clues can be found in our communication. We already see groups as individual identities, e.g., “Google buys Motorola Mobility.” And we often personify groups, like when US political parties are depicted as the anthropomorphized elephant and donkey, or when an over-excited crowd is said to have a “mob mentality,” or when a news article reads “The Catholic Church believes …” What other than a mind possesses beliefs?

Psychology is sometimes called a “black box” science because it can’t actually see the internal mind, so it develops theories based solely on observing people’s external behaviors. Are social groups external minds? Can studying their structures and interactions reveal how internal minds function?

In sociology, a social organism is a theoretical concept in which multiple organisms act collectively as a single organism. How might we differentiate between the body and mind of a social organism?

The concept of the macro-mind can be taken to the cosmological level. Models of the universe appear to resemble brain slices to an almost uncanny degree as depicted in this image from a New York Times article. The implications of substrate independence are literally astronomical.

Determining whether micro- and macro-minds exist is a matter of defining what a mind is. And that, unfortunately, is a matter that’s been debated for thousands of years.

Observations of time

Time is especially peculiar. Mathematically, it’s a dimension just like space. But time is perceived far differently. There is no direct evidence for the past or future, for instance. They cannot be observed. There is also the unexplained ‘velocity’ of time. It passes all on its own. What accounts for these profound differences between time and space?

Continue reading