There is no way that I can explain or give a complete account of a cat using merely the molecules and processes that make up the cat. I could, of course, list them all. But ultimately they would still be a list of physical processes and wouldn’t supervene on what a cat is. One of the reasons for this is because different cats have shared properties but also have sufficient differences such that their physical structures are never exactly the same. It seems that one can’t even do this in principle.

What then is the ultimate difference in explanation between this and giving a complete account of consciousness? Note that of course they are different things but with respect to explanation, how is any one problem harder?

  • The hard problem has little to do with giving a "complete account" of any particular consciousness, or even of properties that all consciousnesses share. It only asks to explain, in principle, how relational descriptions could account for phenomenal feels. A toy model would be enough. If anything, it is more like explaining how cats manage to land on their feet, which toy models explain well enough.
    – Conifold
    Commented Apr 11 at 11:56
  • But what about what physical reality actually represents? Relational descriptions are merely descriptions and descriptions by the nature of language can’t fully capture what’s going on out there. What’s the difference between descriptions not being able to capture reality as it is actually vs. phenomenal feels? Commented Apr 11 at 12:04
  • 2
    Descriptions are able to capture plenty, and nobody is asking for "reality as it is actually is", just a schematic outline of one narrow aspect. Perhaps, not even by descriptions that we currently use, but some enhancement thereof.
    – Conifold
    Commented Apr 11 at 12:40
  • This is actually a good question. There is a difference between defining something like the word "cat" and defining the word "consciousness." Consciousness is somehow essential, whereas a word like "cat" could be defined in many different arbitrary slightly different ways with convention being the only reason to prefer one definition over another. But what is it about consciousness that makes us think a definition of it could fail for reasons beyond just convention?
    – causative
    Commented Apr 11 at 15:58
  • This appears to shift the goal posts from a cat to cats (plural), a physical cat to the concept of a cat. It is not a given that you can't explain a cat by specifying all of its components, or a consciousness by detailing all of the neurons and associated biochemistry. So there are actually four problems here (and the additional one of the ambiguity in the way the question is posed). Commented Apr 11 at 17:15

3 Answers 3


Sure, the cat is more than the aggregation of its parts, How and why this "more" exists, is in fact the hard problem regarding consciousness. A living being is "living" by definition, not because of something is causing it to be "living"! Of course things can cause the state of non-living : death, but it's not working the other way around. Life, so as consciousness are emergent phenomena.


I remember discussing consciousness with like-minded school chums after a physics class in which we had been introduced to the principles of dimensional analysis. If you're not familiar with dimensional analysis, it just relates to the fact that since physics uses equations, and since by definition the parts of an equation either side of the equals sign are the same, that means that they must have the same dimensions. For example, take the familiar relationship that force equals mass times acceleration. The dimensions of force must therefore equal mass times distance over time squared. Back to my schooldays... so we reflected on the fact that in order to have a physical theory of consciousness, you might have to be able to express the dimensions of consciousness in terms or other physical dimensions- such as time, mass, charge, distance etc- and that seemed impossible. I think in a sense that typifies the hard problem of consciousness, which is that consciousness seems so fundamentally different from anything else for which we have physical explanations that it seems impossible to express consciousness in terms of other conceptual building blocks.

It is possible in principle to give a detailed account of a cat, if you leave aside the possibility that the cat has consciousness. We can say that the cat is made up of molecules, that they interact in various ways according to the laws of physics, we can say how arrangements of molecules form cells, how they metabolise energy, why their fur has a particular colour etc etc etc. We can reduce all those things to physical concepts such as energy, force, mass, charge and so on. However, we can't even begin to express consciousness in similar terms.


As a phenomenon, no real difference as both the cat and consciousness are objects of experience, but as something capable of free will, conscious beings also have a unique experience of freedom. That experience can perhaps be explained by physical processes, but thoss processes don't help me to decide who to vote for in the next election, they don't replace the necessity of acting with intent.

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