How Can We Possibly Tell If It’s Conscious?
April 18, 2002 by Ray Kurzweil
At the Tucson 2002: Toward a Science of Consciousness conference, Ray Kurzweil addressed the question of how to tell if something is conscious. He proposed two thought experiments.
Excerpted from a slide presentation at Tucson 2002: Toward A Science of Consciousness
April 10, 2002
Thought Experiment 1: Create Ray 2
- Make a copy of all the salient details of me.
- Ray 2 has all of my memories, so he remembers having been me.
- He recalls all of my memories.
- If you meet him, you would be convinced he is Ray (he passes a Ray Turing Test).
- You could do this while I was sleeping, so I may not even know about Ray 2.
- If you tell me that we don’t need Ray 1 anymore, I may beg to differ.
- I may come to believe in Ray 2’s existence, but I would consider him someone else..
- Ray 2’s continued existence does not represent immortality for me.
- Copying me does not transfer my consciousness because I’m still here… Okay, so far so good.
Thought Experiment 2: Gradual Replacement of Ray
- Replace a tiny portion of my brain with its neuromorphic equivalent.
- Okay, I’m still here… the operation was successful (eventually the nanobots will do this without surgery).
- We know people like this already (e.g., people with cochlear implants, Parkinson’s implants, other neural implants).
- Do it again… okay I’m still here… and again…
- At the end of the process, I’m still here. There never was an old Ray and a new Ray. I’m the same as I was before. No one ever missed me, including me.
- Gradual replacement of Ray results in Ray, so consciousness and identity appears to have been preserved.
- HOWEVER…
However…
- Ray at the end of the gradual replacement scenario is entirely equivalent to Ray 2 in the mental porting scenario.
- Ray at the end of the gradual replacement scenario is not Ray but someone else.
- But in the gradual replacement scenario, when did Ray become someone else?
- The gradual replacement scenario is entirely equivalent to what happens naturally:
   Most of our cells turn over within a month or a few months.
   Those that persist longer (e.g., neurons) nonetheless replace their particles. - So are we continually being replaced by someone else?
This is a real issue wrg Cyronics
- Assuming a preserved person is ultimately reanimated, many of the proposed methods imply that the reanimated person will be rebuilt with new materials and even entirely new neuromorphically equivalent systems.
- The reanimated person will, therefore, effectively be Ray 2 (i.e., someone else).
There is no objective (third party) test for subjectivity (first person experience aka consciousness)
- If Ray 2 happens to be nonbiological:
   He would have all of the same abilities to understand his own situation, the same feedback loops.
   The activity in his nonbiological brain would be comparable to Ray 1.
   He would be completely convincing to Ray’s friends.
   But there is no way to experience his subjective experiences without making philosophical assumptions. - Machines today are not convincing, but they are still much simpler than human intelligence.
- But this gap will be closed, and future machines will be convincing in their emotional intelligence.
- But there remains an inherent objective gap in assessing the subjective experience of another entity.
The Hard Issue of Consciousness
- Only becomes a scientific question when one makes certain philosophical assumptions.
- Some people conclude that consciousness is an illusion, that there is no real issue.
- Consciousness is, therefore, the ultimate ontological question, the appropriate province of philosophy and religion.
- So my philosophy is…
… Patternism
- Our ultimate reality is our pattern.
- Knowledge is a pattern as distinguished from mere information.
- Losing knowledge is a profound loss.
   Losing a person is a profound loss. - Patterns persist.
   The pattern of water in a stream
   Ray - We are still left with dilemmas because patterns can be copied
We will ultimately come to accept that nonbiological entities can be (are) conscious
- But this is a political and psychological prediction.
- There is no way to demonstrate this without making philosophical assumptions
You all seem conscious, but
- Maybe I’m living in a simulation and you’re all part of the simulation.
- Or (at the end of the conference), perhaps I only have memories of you, but the experiences never actually took place.
- Or, maybe I am only having a conscious experience of recalling memories of you but neither you nor the memories really exist.
- Or, perhaps…
Ray Kurzweil’s The Law of Accelerating Returns essay includes further discussion of these issues about consciousness.