Interesting. I have thought about these questions a lot, and came to a possibly different conclusion about verifying the reality of a tree.
<spoiler?>
All you can be certain of is the existence and content of your own experience, in the present moment. You currently experience looking at a tree. Now you experience remembering looking at that tree as you ponder the question “How do I know if the tree is real?”
Your present experience comes with access to this think you seem to call “memory”. In particular, some memory is “episodic”. The type signature of “episodic memory” feels vaguely similar to that of an experience. This, and your intuitive sense of mostly-linear time, are enough to reasonably guess that past memories actually correspond to experiences, and that these experiences seem to form a linear order called “time”. By observing memories of having observed memories, you conclude that an experience only has access to those before it on its time-curve, and that these memories are somewhat unreliable and imprecise.
You notice that the “visual sensory input” part of your experience contains data on multiple levels of abstraction, spanning from the texture of a red smudge on a ball to the fact that there is a ball in the first place. You call the latter type of data “object detection”. You notice that nearby time-slices of experience mostly share detected objects (object permanence).
Based on memories of experiences containing observations of “humans” and on experiences of interacting with these humans and of observing your own physical body in various ways (e.g. via mirrors, generalizing their apparent effect on your viewing of other objects to yourself), you notice that your physical presence is of a similar type to these “humans”, and conclude that the experience that is you is simply that of a human, and so other humans have similar experience. Thus, experiences interact with one another in at least two ways: first is through episodic memory, and second is through physical interaction between the carriers of said experience.
You notice that the medium through which both kinds of these interactions, along with most sensory observations, seem to occur, (“physical reality”) very stably obeys certain rules, including a more general form of object permanence, which you refer to as “existence” of a particular object.
You note that the way you conceptualize and use language was pretty much entirely learned from interaction with other nearby humans, and conclude that, at least for the most basic things like object detection, humans mostly use the same words to describe the same things. Thus, the exact meaning of “existence” as it relates to the tree is pretty much agreed upon.
According to your memory you saw the tree. You also touched and felt the tree. You noticed that the tree grants you the ability to remain suspended above the ground for a lot longer than you otherwise could, via you climbing it. You talk to others and confirm that they also observed the tree through multiple channels. You conclude that the tree exists.
Interesting. I have thought about these questions a lot, and came to a possibly different conclusion about verifying the reality of a tree.
<spoiler?>
All you can be certain of is the existence and content of your own experience, in the present moment. You currently experience looking at a tree. Now you experience remembering looking at that tree as you ponder the question “How do I know if the tree is real?”
Your present experience comes with access to this think you seem to call “memory”. In particular, some memory is “episodic”. The type signature of “episodic memory” feels vaguely similar to that of an experience. This, and your intuitive sense of mostly-linear time, are enough to reasonably guess that past memories actually correspond to experiences, and that these experiences seem to form a linear order called “time”. By observing memories of having observed memories, you conclude that an experience only has access to those before it on its time-curve, and that these memories are somewhat unreliable and imprecise.
You notice that the “visual sensory input” part of your experience contains data on multiple levels of abstraction, spanning from the texture of a red smudge on a ball to the fact that there is a ball in the first place. You call the latter type of data “object detection”. You notice that nearby time-slices of experience mostly share detected objects (object permanence).
Based on memories of experiences containing observations of “humans” and on experiences of interacting with these humans and of observing your own physical body in various ways (e.g. via mirrors, generalizing their apparent effect on your viewing of other objects to yourself), you notice that your physical presence is of a similar type to these “humans”, and conclude that the experience that is you is simply that of a human, and so other humans have similar experience. Thus, experiences interact with one another in at least two ways: first is through episodic memory, and second is through physical interaction between the carriers of said experience.
You notice that the medium through which both kinds of these interactions, along with most sensory observations, seem to occur, (“physical reality”) very stably obeys certain rules, including a more general form of object permanence, which you refer to as “existence” of a particular object.
You note that the way you conceptualize and use language was pretty much entirely learned from interaction with other nearby humans, and conclude that, at least for the most basic things like object detection, humans mostly use the same words to describe the same things. Thus, the exact meaning of “existence” as it relates to the tree is pretty much agreed upon.
According to your memory you saw the tree. You also touched and felt the tree. You noticed that the tree grants you the ability to remain suspended above the ground for a lot longer than you otherwise could, via you climbing it. You talk to others and confirm that they also observed the tree through multiple channels. You conclude that the tree exists.
</probably-not-much-of-a-spoiler>