Can you imagine a tiger? (Look at it from the side rather than from in front)
If so, do it.
Do you see a mental image?
Does it have stripes?
Now, count the stripes.
How many are there?
Some people can count them. I can't. Some people can't see the tiger at all.
I can't even tell if I'm in the stripe-counting category or not. I can imagine tigers with 20 stripes. And I can count the stripes on those. But my initial tiger had stripes which I couldn't count. What the hell do I mean by 'mental image'? I can't imagine a physical image which has stripes that I can't count!!!
On the other hand, if I imagine a zebra crossing, that's got five stripes. But I can't tell you whether that's the real answer, or even if different zebra crossings have different numbers.
Apparently there was once a great philosophical debate about whether 'imagination' was just an over-extended metaphor. Some philosophers claimed that people couldn't see mental images, just that they had grown so attached to the idea as a metaphor for what actually happens that they couldn't let it go.
Other philosophers thought the first lot of philosophers were lunatics, or just pretending in order to be provocative.
The debate was settled when Francis Galton found out that it worked differently for different people.
I don't actually know whether that's true or not. I just read it on the internet at random. But the very idea that it might be true is blowing my mind. This is much more profound than the child's question 'Is the blue that you see the same as the blue that I see, or do we call different sensations by the same name?'.
To suddenly conceive, at the age of forty, that peoples' consciousnesses could be that different is really freaking me out.
I've never had the slightest trouble imagining that everyone except me is a 'philosophical zombie'. And, since there's no way to tell, I've an open mind on the idea that only some of us are conscious, and the rest are zombies.
But this is weird. It turns out that some of you are aliens!
Hmm, thinking about it, I just used the word 'imagining' for something I have no image of.
Panicking now. If you're reading this post, could you leave a comment with your answers to the tiger-questions?
And actually, on the zombie question, if you're reading this post and you're not conscious at all, could you leave a comment to that effect?