Consciousness: the Hard Problem

• A. René Descartes
• B. David Chalmers ✓
• C. Thomas Nagel
• D. Daniel Dennett

Why: David Chalmers introduced the distinction between the 'easy problems' and the 'hard problem' of consciousness in his 1995 work, highlighting why explaining subjective experience is distinctively difficult.

• A. Why there is something it is like to see the color red
• B. Why subjective experience accompanies brain activity at all
• C. How the brain integrates information from different senses ✓
• D. Why pain feels painful from the inside

Why: Integrating sensory information, along with discriminating stimuli and controlling behavior, are functions that can in principle be explained by cognitive and neural mechanisms. The hard problem concerns why these processes are accompanied by subjective experience at all.

• A. The ability to react to environmental stimuli
• B. The capacity to make decisions based on goals
• C. The qualitative, subjective feel of experiences ✓
• D. The brain's ability to store memories

Why: Phenomenal consciousness refers to the felt, qualitative character of experience, such as how an itch or a sunset feels to the one having it. This is the central target of the hard problem.

• A. Bats have no conscious experience
• B. Subjective experience cannot be fully captured by objective, third-person physical descriptions ✓
• C. Consciousness is identical to neural firing patterns
• D. Animals cannot be studied scientifically

Why: Nagel argued that facts about what it is like to be a particular organism are inherently subjective and resist objective physical description, pointing to a gap that physicalist accounts struggle to close.

• A. Because the brain is too complex to study
• B. Because explaining brain functions does not automatically explain why those functions are accompanied by experience ✓
• C. Because neuroscience has already solved it
• D. Because consciousness exists outside the physical brain

Why: Even a complete mechanistic account of brain processes might leave open why those processes feel like anything. The hard problem asks for an explanation of this experiential dimension, which goes beyond describing functions and mechanisms.

• A. A being that behaves exactly like a conscious human but has no subjective experience ✓
• B. A being that lacks the ability to speak or reason about its own mental states
• C. A robot programmed to simulate human emotions with no internal processing
• D. A person suffering from a neurological disorder that eliminates sensation

Why: A philosophical zombie is a hypothetical being physically and functionally identical to a conscious human but lacking any subjective, phenomenal experience. Chalmers uses the conceivability of such beings to argue that consciousness cannot be fully explained by physical facts alone.

• A. Two people could have identical brains but different languages
• B. Two people could have the same functional color discrimination while experiencing colors differently in their subjective quality ✓
• C. Colors can only be perceived correctly when light passes through a prism
• D. Animals perceive a wider range of colors than humans do

Why: The inverted spectrum hypothesis imagines that your experience of red might be how I experience green, while our behavior and discriminations remain identical. This suggests that the qualitative character of experience is not fixed by functional or behavioral facts.

• A. That physical facts are irrelevant to the mind
• B. That physicalism is false, since a physically identical world lacking consciousness is conceivable ✓
• C. That all conscious beings are made of silicon
• D. That behaviorism is the only correct theory of mind

Why: If a world physically identical to ours but without consciousness is conceivable, then consciousness is not logically entailed by physical facts. Chalmers takes this to show that physicalism is false, since physicalism holds that physical facts necessitate all facts, including conscious ones.

• A. Daniel Dennett
• B. John Searle
• C. Frank Jackson ✓
• D. Thomas Nagel

Why: Frank Jackson introduced the knowledge argument in 1982, imagining Mary, a color scientist raised in a black-and-white room. Jackson argues that when Mary first sees red, she learns something new, suggesting physical information does not capture everything about experience.

• A. Conceivability is a matter of what we can imagine without contradiction, while possibility concerns what could actually be the case ✓
• B. Conceivability applies only to mathematics, while possibility applies to physics
• C. Possibility is always known a priori, while conceivability requires empirical testing
• D. There is no difference; the two terms are interchangeable in philosophy

Why: Chalmers distinguishes between prima facie conceivability (what seems coherent to imagine) and ideal conceivability (what remains coherent after careful reflection). He argues that ideal conceivability is a guide to metaphysical possibility, which is what matters for his anti-physicalist argument.

• A. The difference between what neuroscientists can measure and what they can predict about behavior
• B. The apparent failure of physical or functional explanations to account for why physical processes are accompanied by subjective experience
• C. The time lag between a stimulus and a conscious perception
• D. The gap in scientific knowledge about the structure of the human brain

• A. The view that consciousness exists independently of any physical substrate
• B. The view that everything that exists is ultimately physical or supervenes on the physical
• C. The view that only mental states are real and physical objects are illusions
• D. The view that the mind is a non-material substance interacting with the body

• A. The Chinese Room, in which a person manipulates symbols without understanding Chinese
• B. The Inverted Spectrum, in which two people have swapped color experiences without behavioral difference
• C. Mary the color scientist, who knows all physical facts about color vision but has never seen red
• D. The Zombie World, in which physical duplicates lack any inner experience

• A. Consciousness can be produced by many different physical systems, such as brains and possibly silicon circuits
• B. Consciousness can be experienced in many different languages
• C. Each conscious experience can be divided into several distinct parts
• D. Consciousness appears at many different stages of human development

• A. The hard problem concerns why and how physical processes give rise to subjective experience, while the easy problems concern functional capacities such as attention and memory
• B. The hard problem is unsolvable in principle, while the easy problems are solvable with enough data
• C. The hard problem involves quantum physics, while the easy problems involve classical neuroscience
• D. The hard problem concerns animal consciousness, while the easy problems concern human consciousness

• A. She has never seen any colors but has experienced colored objects through touch
• B. She has complete physical knowledge of color vision, neuroscience, and light wavelengths but has only ever seen in black and white ✓
• C. She has no scientific training and knows nothing about the physical world
• D. She has seen colors through a television screen and understands color perception poorly

Why: Mary is a brilliant scientist who knows every physical fact about color and color vision, yet she has lived in a room where everything is black, white, or grey. The setup is designed to isolate whether knowledge of physical facts exhausts all knowledge.

• A. Mary learns nothing new because she already knew all the physical facts
• B. Mary learns something new, so physical facts do not capture all knowledge, which supports the claim that consciousness is not purely physical ✓
• C. Mary becomes colorblind as a result of the experience
• D. Mary's knowledge of neuroscience is shown to be incorrect

Why: Jackson argues that Mary gains genuinely new knowledge about what it is like to see red. Since she already had all physical knowledge, the new knowledge must be non-physical, which challenges physicalism about consciousness.

• A. A scientific theory about how neurons fire during perception
• B. A concept that picks out an experience by way of the experience itself, such as the concept of 'red' as it is grasped when one is having a red experience ✓
• C. A mathematical model describing the wavelengths of visible light
• D. A word that only philosophers are able to understand

Why: Phenomenal concepts are ways of thinking about experiences that are tied to having those experiences. Physicalists such as Loar and Papineau use this idea to explain why Mary's new knowledge does not show that physical facts are incomplete.

• A. Mary never really learns anything when she sees red
• B. Mary acquires a new way of representing the same physical fact, rather than a new fact ✓
• C. Mary's experience proves that dualism is correct
• D. Mary forgets all her physical knowledge upon seeing color

Why: The 'ability hypothesis' (Lewis) and phenomenal concept strategy (Loar, Papineau) hold that Mary gains new ways of thinking about or abilities regarding a fact she already knew physically, so no non-physical fact is needed.

• A. Because it shows that neuroscience is useless for understanding vision
• B. Because it argues that some truths about experience seem to be left out of any complete physical description, suggesting that physical facts alone are not enough ✓
• C. Because it proves that color does not exist in the physical world
• D. Because it claims that Mary is a fictional character who cannot be studied

Why: The argument targets physicalism's claim that all facts are physical facts. If Mary learns something new about experience despite complete physical knowledge, then experiential facts appear to escape physical description, which is the core of the hard problem of consciousness.

• A. Only human beings possess consciousness
• B. Consciousness is a fundamental and widespread feature of reality, present in some form even in very simple physical systems
• C. Consciousness is produced solely by complex neural computation in brains
• D. Consciousness does not exist and is an illusion created by language

• A. How to combine different scientific theories of consciousness into one framework
• B. How micro-level conscious experiences of fundamental particles could combine to form the unified conscious experience of a whole organism
• C. How to combine physical and mental vocabulary in philosophical arguments
• D. How brain regions combine information to produce memory

• A. The experience of tasting wine
• B. Many separate micro-subjects of experience, such as those in neurons or particles, somehow fusing into a single subject like a human mind
• C. The way a thermostat regulates temperature
• D. The process by which DNA is replicated

• A. Because panpsychism denies that matter exists
• B. Because it is unclear how many small subjects of experience could merge into one unified subject without a clear, non-arbitrary account of the mechanism
• C. Because it requires consciousness to be measurable in laboratories
• D. Because it claims that animals have no minds

• A. Rene Descartes
• B. David Chalmers and Philip Goff
• C. Immanuel Kant
• D. John Searle

• A. Phenomenal consciousness exists and is non-physical, as dualists hold.
• B. Phenomenal properties are not what they seem to be; the sense that experience has intrinsic, ineffable qualities is a cognitive illusion.
• C. Consciousness is identical to a specific type of neural firing pattern.
• D. Only humans can have experiences, and animals merely simulate them.

• A. David Chalmers
• B. Thomas Nagel
• C. Daniel Dennett
• D. John Searle

• A. Because they believe the hard problem has already been solved by neuroscience.
• B. Because the hard problem assumes phenomenal properties that, on their view, do not actually exist in the way we introspectively represent them.
• C. Because they think consciousness cannot be studied scientifically at all.
• D. Because they argue that all questions in philosophy of mind are meaningless.

• A. Direct, infallible access to a non-physical inner light.
• B. Introspection systematically misrepresents our own cognitive states, producing a false impression of mysterious qualia.
• C. The influence of religious belief on human self-perception.
• D. The fact that consciousness is a fundamental feature of the universe.

• A. It accepts too much of the physical world as real.
• B. It seems to deny the obvious datum that we are conscious, since an illusion of experience still requires something to be experienced.
• C. It relies on quantum mechanics, which is not relevant to minds.
• D. It makes consciousness too easy to explain through behavior alone.

• A. The subjective, felt quality of an experience
• B. Information being available for use in reasoning, reporting, and guiding action ✓
• C. The brain's ability to store long-term memories
• D. The physical connection between neurons in the cortex

Why: Access consciousness is defined functionally: a mental state is access-conscious when its content is globally available to the systems that control reasoning, verbal report, and behavior. Block contrasts this with phenomenal consciousness, the subjective feel of experience.

• A. Remembering a phone number so you can dial it
• B. Using a stop sign's color to decide to brake
• C. The distinctive redness you experience when looking at a ripe tomato ✓
• D. Reporting to a friend that you feel tired

Why: Phenomenal consciousness is the 'what it is like' aspect of experience. The subjective redness of a tomato is a felt quality, which is precisely what the hard problem asks us to explain, whereas the other options describe functional roles that access consciousness can capture.

• A. Consciousness requires a single brain region dedicated to self-awareness
• B. Information becomes conscious when it is broadcast widely across many brain systems ✓
• C. Consciousness exists only in the prefrontal cortex and nowhere else
• D. Conscious states cannot be studied through brain imaging

Why: Global workspace theory proposes that specialized unconscious processors compete for access to a limited-capacity workspace. Content that wins access is broadcast across the brain, making it available for report and action, which maps naturally onto access consciousness.

• A. Brain scans are too expensive to be useful
• B. Explaining the functions and neural correlates of experience may not explain why those processes feel like anything at all ✓
• C. Neurons are too small to be involved in conscious thought
• D. Neuroscience has already fully explained consciousness

Why: Even a complete account of which brain processes correlate with experience, and what functions they perform, seems to leave open why those processes are accompanied by subjective feeling. This explanatory gap is the core of the hard problem.

• A. Explaining how the brain processes visual information and integrates it for behavior ✓
• B. Explaining why people fall asleep at night
• C. Determining the exact number of neurons in the human brain
• D. Deciding whether animals have consciousness

Why: David Chalmers coined the 'easy problems' to describe questions about cognitive functions such as discrimination, integration, attention, and report. These are hard in practice but are in principle explainable through standard mechanistic science, unlike the hard problem of explaining subjective experience.