(Now with Part 2.)
Life, for instance, does not exist. I can define it; everything that lives can be assigned a goal. At the very least, it strives to stay alive.
Nevertheless, it does not really exist. There's no physical difference between 'living' matter and 'dead' matter, aside from this abstract, 'goals.'
Apparently, these logical abstracts are somehow separate from physics, which is something interesting I have to think about. They are completely consistent with physics, and objective - aliens can easily come up with the same concepts, life and goal, and discover the logical relationship between them. But, they are clearly separate from physics.
Anyway, I similarly seem to have bowls, one of which I'm currently eating out of. But a bowl is an arbitrary designation - it's really just an arrangement of leptons and quarks. The attachment between 'bowl' particles just happens to be much stronger than with 'non-bowl' particles. If I routinely applied bullet like pressures, I would not consider my bowl to be solid. It's a quantitative difference, not a qualitative one - I cannot test a sample and decide it came from a bowl, except by first making an arbitrary definition of bowl. By contrast, I can always tell if something is hot or cold, what kind of atoms it's made of, what the forces between them are, and so on. Aliens cannot rationally disagree with me, while there are many situations under which they would disagree about the bowl-ness of my bowl.
The same thing happens temporally - if a moment to me were millions of years, I would see the bowl decaying rapidly.
In other words, the designation 'solid bowl' happens to work on this particular object due to the myriad details of the particular situation - it is emergent.
On the opposite end, I might be very small, light, and fast. Liquid surfaces would seem very solid to me, and I would be able to shape them like (very hard) snow, because they wouldn't fall fast enough for me to care.
Most educated people believe that consciousness is the same way - it doesn't actually exist, as such. It is 'emergent' just like living things and solid bowls.
This would mean that, for instance, suffering is arbitrary, just like the bowl is. It would be an accident of details.
This view is the only known fatal attack on my theory of consciousness. If indeed consciousness were not real, its existence hardly needs to be explained. Alternatively, you could say that since it doesn't exist, the question of causality and physics is quite irrelevant.
However. The idea that consciousness isn't real is clearly incoherent, though I cannot yet say why. Aliens cannot refute the idea that you suffer. There's no internal structure to reduce suffering to, like there is with life and bowls. Suffering exists by the simple fact that we suffer.
I simply cannot yet prove this.