Can Knowledge Reach Consciousness?

Diego’s worldview on consciousness

There is a rather important guest somewhere in this room. You can observe the guest’s behavior, inspect the guest’s brain, and record the guest explaining in great detail that being a guest feels like something. Diego’s question is whether any of those accomplishments reaches the thing the guest was talking about.

His concern is not merely how a brain processes information. It is the relationship between the machinery we can describe and the experience we want to preserve. This question brought him into philosophy, complicated his hopes for uploading, and eventually sent him toward the biological organization of selves. It also produces one of his most persistent reversals: what if the difficulty is not that our knowledge of consciousness is unfinished, but that knowledge, as a physical process, cannot do the job we keep assigning to it?

The important thing, please

In his 2008 introduction to the subject, Diego asks readers to imagine what religious people hope survives death, then discard the ghostly vapor and cinematic accessories. What remains is the part they actually care about:

Think about the important thing, the one that you would like that remained preserved.¹

His term for that target is phenomenal consciousness: the felt aspect, the redness, the pain, the pleasure, what it is like for an experience to occur. It is not simply possessing information, producing an answer, or knowing where one’s limbs are.

That distinction gives his philosophy its stakes. A future could contain extraordinarily intelligent systems, magnificent architecture, abundant production, and eloquent descriptions of happiness. Diego wants to know whether anyone is there to enjoy it.

He had already posed the nightmare in 2007:

Suppose then that everyone on earth uploads himself to this binary computers, then we would have a fantastic posthuman society, with no one to see it.²

This is a thought experiment in that essay, not a declaration that digital systems necessarily lack experience. The catastrophe he wants the reader to notice is that intelligence and experience are different targets. A civilization could preserve the performance while losing the thing for which the performance was valuable.

The lights are spectacular. It would be unfortunate if the audience had been removed during the upgrade.

Two meanings of consciousness, one expensive confusion

In Can Knowledge Reach Consciousness?, Diego separates phenomenal consciousness from access-consciousness. The latter concerns information arranged so that it can be used in particular ways: reporting, deliberating, remembering, making choices, guiding certain kinds of action.

He explains:

Access-consciousness is all about the information that is structured into our brains in such a way that it has access to some privileged output routes.³

Privileged does not mean supernatural. It means routes that distinguish something one can report or use in active reasoning from, for instance, a metabolic process that affects behavior without becoming something one can describe from within.

This kind of access can be analyzed structurally. Information comes in; a system stores or transforms it; some of it becomes available to certain operations. Diego’s point is that this description does not already contain the felt redness of red. We must not define the two so that a bridge between them appears simply because the vocabulary was arranged to produce one.

The paper says:

Access-consciousness is therefore a definition concerning a kind of access to information, which could be thought of without having to think of phenomenal consciousness.⁴

An excellent account of access may tell us why a person notices something, remembers it, and says it happened. It is an account of those capacities. Whether it also reaches phenomenal experience is the question, not a prize automatically included with the purchase.

The philosopher’s argument is made of the same world as his pen

Here is the central move. Knowledge is not a ghostly spectator outside the physical world. An article exists as ink, stored bits, sounds, neural structures, or some other physical realization. A thought about experience is itself an event in the nervous system. It has a history that can be described in physical terms.

Diego puts it this way:

Knowledge can be written, spoken, coded, represented and can come also in some other forms, but in all its forms, it is physically embedded.⁵

His paper takes physical causal closure as its working setting: the physical events can be accounted for within a self-sufficient physical causal story. Now add a phenomenal realm that does not need to enter that story. The question is how the physical article could acquire knowledge of that addition.

The philosopher’s insistence that the addition exists, the philosopher’s experience of certainty, the movement of his fingers, and the publication of his book all occur in the physical sequence. If that sequence is sufficient, an extra phenomenal property cannot establish its credentials merely by pointing to the book that the physical sequence already explains.

This is the paper’s blunt thesis:

Knowledge cannot access phenomenal-consciousness, and therefore we have no epistemic justification for our theories about phenomenal-consciousness.⁶

That sentence describes Diego’s argument, including its severity. He is not saying that philosophers have been mildly underfunded and could use a better microscope. He is asking whether the alleged object can reach the process that claims to know it.

He gives the restriction an almost comic economy:

There is no what is it like to be knowledge.⁷

A theory is information. It need not itself have the experience it describes. The difficulty, for Diego, is that everything which makes it that theory, rather than another, belongs to a relational and physical account. Adding a nonfunctional phenomenal property does not automatically change any of those relations.

The ghost has been invited to the conference. It has not been given a microphone connected to the recording system.

Whiteblack is having a less colorful time, allegedly

To isolate the issue, the paper introduces Whiteblack, a counterpart of an ordinary person whose physical structure and dispositions are identical, but whose phenomenal experience is restricted to black and white. In the imagined case, the ordinary person and Whiteblack answer alike, behave alike, and express surprise at the same things.

Diego writes:

Even though to be Whiteblack is a much impoverished condition, their access-consciousness is the same, they are constantly able to access the same information (even though different tokens of it).⁸

Whiteblack does not gasp at a color that his counterpart finds routine. His gasping is part of the stipulated physical and dispositional match. The imagined difference therefore cannot be detected simply by asking for another report. Reports were included among the things held constant.

This maneuver turns a familiar argument in philosophy of mind back on itself. If the phenomenal can vary while the physical and functional facts remain the same, then a belief, a theory, and an exclamation can also remain the same while the phenomenal varies. Diego asks what would then make the theory knowledgeable about the variation rather than merely compatible with one guess about it.

The target is not limited to a separate mental substance. The paper also considers proposals in which the phenomenal is the intrinsic or categorical nature of physical reality. His question follows it there: if all the relations that determine our knowledge remain describable without those additional properties, how does renaming them physical provide access?

He states his view of beliefs in a much later Facebook comment:

I'm a physicalist about beliefs.⁹

And elaborates:

The relevant properties of beliefs are those by which they relate to their content in the world. A phenomenological definition only clutters them.¹⁰

The continuity between the academic argument and the comment-section Diego is unusually clear. Knowledge and belief must be explained through the relations that make them about things. The presence of felt experience is not a definition he wants smuggled into that account.

Why not make an assumption and get on with it?

The manuscript reports a response from Chalmers to an earlier version: assume sufficient coherence between access and phenomenology, and proceed. Diego objects to that route within the paper.

He distinguishes assumptions that let inquiry advance toward a later check from an assumption about a realm inquiry cannot reach. If the proposed barrier is the very absence of access, he argues, making more knowledge on the physical side will not eventually inspect the inaccessible side. The additional theory remains dependent on the assumption that supplied the connection in the first place.

His proposed alternative is:

My suggested assumption: suppose that those truths (phenomenal ones) are unknowable in the first place. We could get things going better and faster in nearby realms of study doing so.¹¹

The humor is dry, but the practical consequence is large. One can study perception, cognition, learning, reports, brains, and the conditions under which people say their experience changes without pretending that the central philosophical obstacle has disappeared. The rest of inquiry is not canceled because one particularly demanding assignment may exceed its jurisdiction.

This position has a history. In the Portuguese essay A Consciência Inexplicável, published in April 2008, Diego called an earlier version inaccessible naturalistic dualism. There he retained an intuitive belief in mental events while treating their existence and connection to the physical as unavailable to proof. The later English manuscript attacks the justification for phenomenal theories more directly. These are stages in his attempt to locate the boundary between conviction, description, and access, not interchangeable labels stamped on twenty years of thought.

The research continues in the rooms next door

A conclusion about inaccessible phenomenality did not make him indifferent to experience. His philosophical project began because he wanted to keep living, and later widened to the quality of the life being kept.

Looking back in 2017, he wrote:

My initial ingress in philosophy of mind had a different goal (not dying, understanding personal identity to see if there were ways to self-preserve by upload or something) That question I have concluded we will not solve in my lifetime.¹²

Then he named the questions attracting him back:

But now my interest is twofold: Which are the maximally pleasurable states and ways to reach them? And what are the most reliable in time good states and how to reach those?¹³

The reader should keep both motivations in view: continuation and quality. Diego is not trying to eliminate experience because experience is unimportant. He is troubled by an explanatory gap precisely because what he wants from the future depends so heavily on who, if anyone, experiences it.

The later Causal Dunes collaboration returns through biology. Rather than beginning with a disembodied subject, it studies organized systems, their self-maintenance, the distinctions that matter to them, and how their boundaries change. It then asks how those facts connect to consciousness.

One especially revealing problem is the Conscious Sorites. Begin with one tightly connected cognitive organization; gradually reduce communication until two organized systems can operate separately. When did one subject become two? The causal changes can be traced. The count of experiencers is a further question. In Causal Dunes V, the collaboration states:

Causal-dune organization may provide the individuation coordinates that a psychophysical theory must fit. It does not yet supply the psychophysical theory.¹⁴

That is the project’s own division of labor. Self-maintenance, semantic relevance, causal unity, phenomenal experience, and moral standing are related questions that must retain their separate names. Otherwise an answer to one slips into the costume of an answer to another.

There is no bored shrug at the end of this room. There is an extraordinarily invested man refusing to let a convenient word assure him that the most important thing has survived. He wants the intelligent future, the pleasurable future, and a future with someone actually there. These three invitations must reach the same party.

Further doors

• Is there anything special about conciousness? Concerns about our posthuman future (2007): the original artificial-intelligence/artificial-consciousness distinction.
• A Consciência Inexplicável (2008): the early inaccessible-naturalistic-dualism formulation.
• Can Knowledge Reach Consciousness? (undated manuscript, preserved in the 2026 archive): the full epistemic argument.
• Returning to Consciousness Research (2017): the shift toward pleasurable and reliably good states.
• Causal Dunes V: The First Cut Mattered (2026), sections 7–10: subject boundaries, substrate, and continuity.

Continue: Causal Dunes