Does reality exist outside our sensorial experience of it?
Imagine that you open your eyes and you have a sensitive experience of looking at a potato. Then you close your eyes and the potato vanishes. You open again your eyes and you have the same visual experience of a potato. Then you close your eyes and you try to touch with the hands what you have visually described as a potato. Still with closed eyes you try to smell in order to understand if the olfactory experience is consistent with the visual and tactile experiences. Finally you get yourself convinced that the potato is there and it exists outside of your sensory experience. It will be there even when you are leaving.
Now, look at the following image:
You see the lighter gray triangle surfaces as pointing towards you. Try to imagine the darker ones pointing upwards and in front of a lighter gray background—or vice versa.
You should experience a ‘Gestalt switch’ between experiencing the triangles as pointing downwards and resting on the dark grey lower plane, or as pointing upwards and resting on a light grey plane.
Clearly you cannot see both the triangles pointing upwards and downwards. Every time you look at them you will see or the triangles pointing upwards or the triangles pointing downwards.
So, when you do not look at them, which one of triangles are there, outside your sensorial experience? The ones with upwards triangles or the ones with the downwards triangles? And how do they transform each other when you do not look at them?
Another way to verify which is true outside your sensorial experience is to ask your friends to look at triangles. Some of them will say to see the triangles pointing upwards and other will say to see the triangles pointing downwards.
This, clearly, suggests that when nobody look at them, there are no triangles pointing downwards nor triangles pointing upward. There are no objective triangles.
Are you yet sure that potato is there even if you do not look at it?