Chapter 2

The Three Premises — And What Science Says About Them

Before we go further, we need to establish what science actually knows about consciousness, because the entire argument that follows rests on scientific premises, not speculation.

Let me be frank: consciousness is one of the great unsolved problems in science. We do not have a complete theory of how subjective experience arises from physical processes. This is sometimes called "the hard problem of consciousness," and it remains a topic of vigorous scientific and philosophical debate.

But the fact that we don't have a complete theory does not mean we know nothing. In fact, we know quite a lot, and what we know is more than sufficient to support the arguments in this book. Here is what the evidence strongly supports:

Premise One: The Production Premise

The structure and functioning of the brain produces behavior, consciousness, and the quality of subjective experience. When you damage the brain, you alter consciousness. Damage the visual cortex, and you lose the ability to see. Harm the hippocampus, and you lose the ability to form new memories. Injure the prefrontal cortex, and your personality changes. Administer anesthesia, and consciousness disappears entirely. When the anesthesia wears off, consciousness returns. The correlation between brain functioning and conscious experience is so tight and so well-documented that it is, for all practical purposes, a well-established finding.

This evidence comes from multiple independent lines of research:

Anesthesia experiments. These deserve special attention because they are so powerful. When a person is put under general anesthesia, their consciousness is completely eliminated, more thoroughly than in sleep. There is no experience of passing time. There is no "you" during anesthesia. And yet, when the anesthesia wears off and the brain resumes normal functioning, consciousness returns. You are back.

A clarification is important here. None of these results settle the hard problem of consciousness, the question of why physical processes are accompanied by subjective experience at all. What they do is constrain viable theories. Any theory of consciousness must be consistent with the tight, systematic relationship between brain structure/functioning and conscious experience. The evidence does not tell us why brains produce consciousness. It tells us, very convincingly, that they do.

Premise Two: The Multiplicity Premise

The specific atoms don't matter; the structure and functioning do, and many different physical configurations can produce identical conscious experiences. As we discussed in Chapter 1, your atoms are constantly being replaced, yet your consciousness continues. What persists is not the material, but the organization. A neuron firing is a neuron firing, regardless of which specific carbon atoms happen to be in that neuron at the moment.

This principle is not unique to consciousness. It applies to everything in physics and chemistry. Two water molecules composed of different hydrogen and oxygen atoms are nonetheless identical in their properties. Two computer processors manufactured from different batches of silicon will run the same software identically. A recipe yields the same dish whether cooked in one kitchen or another. The specific matter does not contribute some unique, irreplaceable essence; it is the arrangement and operation that determine properties.

What does "structure and functioning" actually include? The answer is: everything physical. The term, as used in Ixperiencit Theory, encompasses:

In short, structure and functioning includes every physical property of the brain that is relevant to its operation. And it is this totality, not the specific atoms, that produces consciousness.

Consciousness, the evidence strongly suggests, is substrate independent too. It depends on the structure and functioning of the brain, not on which particular atoms happen to make up that brain at any given moment.

This is not a wild claim. It follows directly from the fact that consciousness depends on brain structure and functioning, and that extremely small variations in the body (like the orientation of a single atom in your left knee) have zero effect on what your brain does. There are an enormous number of slightly different physical states that produce the same conscious state. The mapping from physics to consciousness is many-to-one, not one-to-one.

Premise Three: The Identity Premise

Identical structure and functioning produce identical properties. This is a foundational principle of physics and chemistry. Two water molecules with different atoms but identical structure have identical properties. Two identical computer programs running on identical hardware produce identical outputs. Applied to any physical property other than consciousness, this principle is uncontroversial. The question is whether consciousness follows the same rule — and the evidence strongly suggests it does.

Applied to consciousness, this premise says: identical brain structure and functioning, regardless of where, when, or in what matter it occurs, would produce identical consciousness.

Some people find this premise obvious. Of course identical physical systems produce identical results — that's what "identical" means. Others find it deeply unsettling when applied to consciousness because it implies that their subjective experience is not uniquely tied to their particular body.

I should note that many philosophers reject Premise Three when applied to consciousness specifically, even while accepting it for every other physical property. They argue that consciousness might involve something beyond structure and functioning, something that makes each instance unique in a way that, say, two water molecules are not. We will engage with the strongest version of this objection in Part Four. For now, I ask only that you hold the premise provisionally and see where it leads.

The phrase "sufficiently similar" is important here. Perfect atomic-level identity is almost certainly not required for identity of conscious experience, just as you don't need every grain of sand to be in the same position for two identical sandcastles to have the same shape. There is a tolerance, a margin of physical variation within which the conscious experience remains the same. Determining the exact boundaries of this tolerance is a scientific question that future research will need to address, but the principle is clear.

What These Premises Imply

These three premises are individually mainstream. The Production Premise is accepted by virtually every working neuroscientist. Applied to any other physical property, the Identity Premise is accepted by every physicist. And the Multiplicity Premise is a logical observation about the space of possibilities.

But together, they lead to a conclusion that is anything but mainstream:

You are not limited to one body, one lifetime, or one moment in time. Your consciousness, your ixperiencitness, can in principle be produced by any brain structured and functioning like yours, wherever and whenever the right physical conditions are met.

What About the "Hard Problem"?

At this point, a philosophically inclined reader might object: "But what about the hard problem of consciousness? We don't understand how brain structure and functioning produce subjective experience. Maybe consciousness involves something beyond the physical. Maybe there's an extra ingredient, something like a soul, even if we don't call it that."

This is a fair point, and I want to address it directly.

Consider an analogy. In the 18th century, scientists did not understand how gravity worked. They knew that massive objects attracted each other, and they could predict the strength of this attraction with great precision, but they had no idea why mass produced gravitational attraction. Newton himself said he "feigned no hypotheses" about the underlying mechanism.

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The remaining text (examples, counter-arguments, and longer connective passages) is in the book.

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