To many researchers, consciousness is an impenetrable mystery cloaked in “inner feelings,” “qualia,” and a “subjective view of the world.” It often is referred to as “the hard problem” because not only do we not know where to find it, but we can’t even agree on what it is.
I suggest it is a “hard problem” because we have rejected clear solutions.
Regular readers of this blog have learned from “Do AIs already process information in a way that gives rise to consciousness?” that rather than being vague, mysterious or magical, consciousness is a physical phenomenon shared by all entities.
It can be measured, evaluated, compared, and described in concrete physical terms.
Consciousness is: History + Stimuli —> Responses —> New History —> Responses…
Your consciousness is your entire history plus your new responses to your most recent stimuli, which yields your new history in an unending, unbroken line of: History + Stimuli —> Responses —> New History.
This applies to every entity from atoms to galaxies. The question is not “Is it conscious?” but “How conscious is it?”
This eliminates the “hard problems” like: Is an ant conscious? A bee,? A tree? A dog? An ape? A sleeping human? Etc. These questions are more than hard; they are unanswerable, and that is not a shortcoming of the researchers. It is a shortcoming of the common definitions.
Whether purposely or inadvertently, researchers have made the problem impossible and have rejected any suggestion of a solution, especially a simple, straightforward, non-magical solution. The response to any solution seems to be: “It can’t be that easy. We’ve spent thousands of years debating it and you tell me it’s just History+ Stimuli —> Responses —> New History?”
Here are excerpts from an article in the October 26, New Scientist Magazine, titled “Meeting Eye to Eye, “ by Rowan Hooper:

I recently discovered some scientific research that struck me to the core. I have spent many years exploring biology and the interconnectedness of life. Yet here was something that cut through all the knowledge I thought I had acquired: scientists have found that if male fruit flies are deprived of sex with females, they turn to alcohol.
I took my hand lens, carefully snuck close to a Drosophila and peered into its red, mosaicked eye. We might be separated in evolutionary time by some 780 million years, I thought, but we share fundamental similarities. Natural selection has equipped us both with a brain that functions to improve our survival and that of our offspring.
Is this why both flies and humans, on occasion, seek to douse flames of sexual rejection with alcohol? Just because flies don’t write poetry about it doesn’t mean they don’t experience a rich inner life.
“Inner life” is another phrase, like “qualia” and “subjective,” describing something that supposedly is non-physical, and therefore “hard.” In fact, it describes emotions, which are both physical and straightforward.
We feel emotions, but that is not a mystical experience. It is chemical and electrical, which our brains translate, just as our brans translate photons into color and shape — just as our brains translate waves of air into the experience of music. No magic; just physics and biology.
My encounter with the fruit fly in the kitchen led me on a mission to understand the feelings experienced by other animals, including insects – to explore from a non-human point of view what it means to be conscious. Only a few decades ago, it was scientific taboo to suggest that even chimpanzees had personalities or feelings.
Now, evidence of complex inner worlds in a wide range of non-human animals is mounting. Even “simple” animals make a good case. Fish seem to know themselves. Bees can be pessimistic. Cuttlefish plan for the future.
This is serious stuff, and it is incumbent on us to understand the extent of animal consciousness so that we can treat our fellow organisms with the respect they deserve. But the quest also sheds light on how this most murky and mysterious of attributes evolved, and what it actually means.
The big question is around what philosophers call phenomenological consciousness: having a subjective view of the world. The aptly named “hard problem” of consciousness is to explain not only why we have feelings at all, but to describe the physical basis of that subjective sense.
Here is the scientific description of phenomenal consciousness:
Phenomenological consciousness focuses on what it is like to experience something from the inside, rather than analyzing the physical or neural components of consciousness. It investigates the structures of experience, including time, space, body, self, and world, as they appear to the conscious subject.
Central to this approach is intentionality, the idea that consciousness is always “about” or directed toward objects, events, or states of affairs, whether real, imagined, or abstract. There is no non-intentional sphere of consciousness; every conscious act involves a relation to something.
If that isn’t crystal clear, you now know why it’s called the “hard problem.” Make the definition vague enough and you can be sure the problem will be hard. The “intentional” part makes one think that if you unintentionally fall down, you supposedly aren’t conscious.

Examining the lives of non-human animals can help tackle this notoriously difficult problem, says philosopher Tim Bayne at Monash University in Melbourne. “If we assume there is a kind of subjective experience in an animal,” he says, “what might it be like? What reason would it have to be conscious?”
I turn to Lars Chittka, a behavioural ecologist at Queen Mary University of London. His team’s work has shown that bumblebees engage in what can best be described as play. Chittka made a mini ball pit near the bees’ nest and found that the insects rolled the balls for extended periods.
Not only that, but they seemed to enjoy it, going out of their way to go back to the play area. “It looks like subjective experience. It looks likely they are having emotion-like states,” he says.
It also looks exactly like History + Stimuli —>Responses —>New History. The bee is stimulated by the ball, responds to the ball, and that response adds to the bee’s history. Its so-called “subjective experience” is a physical response by the bee’s brain to the stimulus of play.
One day soon, we will be able to look inside a bee’s brain and see exactly what physical changes occur that result in a bee’s feeling that corresponds to what we call “pleasure.”
It probably will not be the same as ours. But it may resemble the feeling that the bee gets when it tastes nectar or when it sees a bunch of ready flowers.
Other insects seem to engage in play, too. Last year, researchers made an insect amusement park and found that some fruit flies sought out rides on a spinning carousel.
I asked Chittka about the haunting finding that male fruit flies drink alcohol if they can’t have sex. Flies that had recently mated and those that were prevented from doing so were both offered either regular food or food laced with 15 per cent ethanol. The sexually satisfied males ate both types equally, while the thwarted males strongly preferred the booze.
The scientists also identified a neural system that links the rejection to the alcoholic reward. “For me, the observation that if you deprive male fruit flies of the opportunity to have sex, they turn to something that likely makes them feel better, it is highly suggestive that they are experiencing a negative feeling [that] can be remedied with a drug, in this case alcohol,” says Chittka.
The fruit flies’ History included their emotional Response to sexual deprivation. They drank alcohol, a new stimulus, and their Response was to feel better. Now, they had a New History, which included drinking alcohol that made them feel good in some way.
You might object and say that neither play nor self-medication with alcohol is evidence of consciousness. Yet, to many scientists, the findings suggest there is a subjective sense of self held by these animals.
It’s not evidence of consciousness, if the definition of consciousness is so vague, indefinite, uncertain, and unclear that any evidence would be impossible to produce.
A “sense of self” implies that only a higher level intelligence, capable of ruminating about “my life,” can be conscious. But why? What makes that the boundary of consciousness? And how would we know? Does the playing bee have a sense of self, or is it simply playing because that feels good?

“I don’t know how to prove if another individual is conscious, even with humans,” says psychologist Nicola Clayton at the University of Cambridge. But she has tried to probe several animals’ subjective experiences.
In one experiment, her team performed a version of the famous marshmallow test on cuttlefish, testing to see what the creatures would do when offered a choice between one treat (a live shrimp) immediately or two if they waited. Like some children, cuttlefish were able to delay gratification. “It’s an important part of planning for the future,” says Clayton. “I would say that’s good converging evidence that this animal has consciousness.”
Professor Clayton can’t prove anyone is conscious because the definition she is using demands that it remain undefined. The cuttlefish has a history with which it responds to stimuli to create a new history. It therefore, is conscious.
The only question is, “How conscious is a cuttlefish?” and the answer involves the depth and complexity of its history and its responses to stimuli.
Clayton and her colleagues have shown that jays can relive past moments and anticipate future ones. In one 2024 experiment, food was hidden under one of a line of distinctive cups. The watching jay was then removed while the order of the cups was shuffled. When the bird returned to the test chamber 10 minutes later, it could remember the correct cup.
This is good evidence for episodic memory – long-term, event-based memory – and is evident in the wild: jays have evolved to cache food and retrieve it later, and adjust their behaviour to deceive others if they are being watched.
As I assimilate this new thinking on animal consciousness, I find myself moving through the world in a different way. I notice some honeybees landing on cyclamen flowers, and watch the bees carefully for signs of caution. Chittka has shown that if bees encounter crab spiders lurking in flowers, they become nervous when visiting other plants.

That makes sense, because crab spiders are dangerous predators of bees. “Their demeanour changes – they fly slower,” says Chittka, “but false alarms happen.” They will sometimes check out a flower that has no predator, yet still reject it. “It’s as if they’ve seen a ghost,” says Chittka. “Anthropomorphically speaking, it’s like we see in PTSD when people conjure up a threat of something not there.”
Bees aren’t the only seemingly simple creatures with signs of consciousness: the more experiments scientists conduct, the more they uncover animals with complex inner lives. Magpies are one of a growing number of species to have passed the mirror test, and were the first non-mammals shown to do so.
This test aims to assess whether an animal has a sense of self based on its interaction with its own reflection. Perhaps it’s not too surprising that a magpie can do this, but more startling is the finding that a fish – the cleaner wrasse – has also passed the mirror test.
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Will Sowersby at the Arthur Rylah Institute in Australia and his colleagues noted the speed and ease with which cleaner wrasse habituated to a mirror in their tank and started using it to inspect their own bodies.
But then they saw a fish take a piece of shrimp, drop it in front of the mirror, and watch it fall in the reflection. It was as if the fish was a kind of physicist, performing an experiment. “What we were seeing is evidence that an animal can undertake hypothesis testing,” says Sowersby.
“The cleaner fish used a piece of shrimp to test the properties of the mirror. A remarkable observation.”
So now, we have making and playing with toys, episodic memory, delayed gratification, planning for the future, understanding mirrors, hypothesis testing, and avoiding predators, all of which we arbitrarily have designated as evidence of “consciousness” — a word we can’t define clearly.
Amid the various tests, animals’ ability to learn from experience is increasingly considered one of the most important signifiers of consciousness. Jonathan Birch, a philosopher at the London School of Economics, has been working with neurobiologist Simona Ginsburg and geneticist Eva Jablonka on a framework they call unlimited associative learning, or UAL. To evaluate consciousness, they propose measuring five aspects of an animal’s capacity to learn.
Add “capacity to learn” to the list of consciousness evidences. The dictionary definition of “learn” is: to gain knowledge or understanding of or skill in by study, instruction, or experience.
Can you think of any animal that does not gain knowledge from experience? Even an amoeba learns from experience:
- Habituation: An organism gradually reduces its response to a repeated, harmless stimulus. Experiments with certain single-celled organisms suggest that they can exhibit this form of learning.
- Adaptation: An amoeba encounters an unfavorable chemical environment and changes its behavior. If that change persists and influences its response to a later encounter, it may represent learning rather than merely an immediate chemical reaction.
- Cellular memory: Previous stimulation can alter a cell’s internal chemistry, protein activity, or gene expression. Those changes can affect how it responds to subsequent
Slime mold
And, there is stronger experimental evidence for learning-like behavior in other single-celled organisms, including Physarum polycephalum (a slime mold, not a true amoeba). (See: Habituation in non-neural organisms: evidence from slime moulds). So now we are down to amoeba and slime molds exhibiting one of the common criteria for consciousness.
One important aspect is the ability to learn to associate one stimulus with a second, novel stimulus. The classic example is Pavlov’s dogs: the canines learn to associate a bell with food, then they salivate at just the sound of the bell. Fruit flies and honeybees can do this, so these animals, and dogs, tick that box in the UAL checklist.
This sophisticated learning reflects animals’ consciousness, says Birch. “Animals are not just calculators. They don’t just solve puzzles.
Slime molds solve puzzles. And an experienced slime mold can teach an inexperienced slime mold. Experiments have indicated that slime molds even appear to anticipate the timing of recurring unfavorable conditions.
They (animals) also have emotions. They have inner lives in which they feel things, and we can make inferences about these things as well.”
Birch, Ginsburg and Jablonka have combed through the scientific literature to build the case for UAL, and therefore consciousness, in a range of animals. Their work suggests consciousness independently evolved at least three times, says Birch: in vertebrates, where it led to consciousness in birds and mammals; in cephalopod molluscs, where it led to sentient octopuses and cuttlefish; and in arthropods, which created conscious insects, spiders and crustaceans, such as lobsters. “In at least those three lineages, they’ve gone from a non-conscious starting point to having a form of consciousness,” says Birch.
What we are learning from animals helps sharpen the thinking on why consciousness evolved, says Bayne. “The basic purpose of consciousness is to alert you to critical bodily needs: do I need food? Am I too hot? Am I too cold? Am I in danger? Is this a mating opportunity?” he says.
If the purpose of consciousness is to address those variables, then it makes sense why bodily sensations like thirst are so vivid and salient, and so central to consciousness.
That is an example of Teleology: Explaining something in terms of its purpose or ultimate goal rather than its causes. For example, saying that consciousness exists in order to protect an organism. It also is anthropomorphism—attributing human characteristics, intentions, emotions, or motivations to nonhuman entities.
But, Nature has no purposes. Nature has causes and effects. What we call “purpose” is our interpretation of effects that have persisted through natural selection.
The authors are equating emotions with consciousness, but emotions merely are chemical and electrical stimuli. Human brains interpret in certain ways and animal brains may interpret differently.
As we have seen, brains aren’t necessary for consciousness. Even in humans, brains don’t do all the work. We experience and translate stimuli throughout our entire bodies.
The advantage of UAL is that it doesn’t get bogged down in some bigger grand theory for the mind, such as integrated information theory or global workspace theory.
“You say, ‘I don’t care about theories of consciousness. I’m just going to look for behavioural and neural signatures of consciousness and see if they’re similar to what happens in humans,’” says Anil Seth at the University of Sussex, UK.
These approaches avoid directly trying to answer the hard problem of why a physical process is accompanied by a conscious feeling. “I don’t think we make the best progress by going after the hard problem directly,” says Seth. “I think we go after it indirectly, and this is one way of doing that.”
“We don’t need to solve the hard problem to have evidence of consciousness in other systems,” says Birch. “Indeed, it might lead over the longer term to better solutions, because the more evidence you have, the better position you’re in to develop theories about the nature of consciousness.”
We agree wholeheartedly. The so-called “hard problem” tends to be intuitive rather than scientific. The “hard problem” exists only because we assume that subjective experience is something additional to the physical processes themselves.
If subjective experience is defined as something that cannot be explained by physical processes, then no physical explanation ever could satisfy the definition. The “hard problem” becomes permanently insoluble by construction.
Consciousness is the physical process of responding to stimuli according to a system’s history. The so-called hard problem arises when we assume that consciousness must contain something beyond that process, without first establishing that anything beyond it exists.
Rodger Malcolm Mitchell