The previous post talked about qualia, or subjective experiences, but why should we care? This being a matter of philosophy, there are a variety of answers to that, starting with "Why care about anything?" but nonetheless, there seems to be something significant about the question. At least from my own subjective point of view.
For one thing, it seems like one of those fundamental questions. How can we come to a complete understanding of the universe without understanding how we experience it? Perhaps more than that, there are ethical concerns. If we wish to increase happiness or we do not wish to cause unnecessary suffering in the world, we should understand what happiness and suffering are. Outward appearances will only tell us so much. It would be good to have more reliable indicators, or at least to know how reliable the ones we have are.
The problem with subjective experiences, though, is that they are subjective. I can be well convinced that my own subjective experience is real. Sentio ergo sum -- I feel, therefore I am. There are several reasons for me to believe that someone else's feelings are real: I can see their reactions, they can tell me, and we know that humans have, for the most part, essentially the same neural apparatus.
Nonetheless I cannot know for sure what another person's feelings are in the same way that you and I could both put the same object on a balance scale and agree on its mass. Each of the common-sense indications I just gave can fail. Someone may not react visibly to a feeling or experience, or I may not catch the reaction. They may not be able to tell me for any number of reasons. Different people can have different ranges of feeling -- what seems intense to me might seem like nothing special to you, or vice-versa.
From a purely philosophical point of view we don't know for sure that having the same kind of neural pathway means having the same kinds of experiences. Perhaps the ability to experience requires both a certain type of pathway and something else intangible that not everyone has. Even if there is no such intangible, we're still far from knowing what physical pieces are associated with experience, though we do have some clues. Without knowing just what pathways gives rise to subjective experience we have no way to be sure everyone has it.
When we go beyond human experience to other species, which react differently, can't verbalize their experiences (or at least not in ways we can presently understand), and have clearly different neural circuitry, we have even less to go on. We can presume that a dog wagging its tail and barking when its human returns is happy, but it's always possible that dogs have simply co-evolved with us for long enough that they are able to act happy when that would be to their advantage (most people with dogs would dispute this, I expect).
Artificial constructs are even more problematic. If I build a robot that avoids walls even if you push it toward one, it's easy to say "it doesn't like walls" because it's acting like a sentient being that disliked walls would, but it seems a much bigger step to say "it avoids walls because it experiences negative emotions when it's near one", particularly when we can point to the exact code that causes it to avoid walls.
Even if the code for the control system is extremely complex or has gone through some sort of machine learning process to develop an avoidance of walls, so that we couldn't point to exactly what was making it avoid walls, it still seems hard to argue that the robot is feeling emotions. If incomprehensible code were the basis of sentience, there would be a lot of sentient software around.
When it comes to what we generally refer to as inanimate objects, the best we can say is that we have no reason to believe that a rock feels pain if we smash it with a hammer. Nothing in our understanding of how we feel pain seems to apply to something like a rock. Even so, how can we really know?
But how do we know anything? We have no way of knowing whether we really live in a universe where the laws of physics hold. It's possible that tomorrow things dropped will fall up instead of down. Some theories of cosmology assign a non-zero (but still exceedingly small) chance that we live in such a universe.
In the absence of certain knowledge all we can do is try to build a coherent framework and constantly test and adjust the assumptions it rests on, a process we call "science". From a scientific point of view we can figure out what sort of neural structures correspond with the subjective experiences that people report. We can assess whether other organisms have such structures and even whether a particular combination of hardware and software has something functionally equivalent.
We can tell whether something's reactions to various stimuli are consistent with it having such capabilities, based on what people have reported. We can conclude from that that it's likely or unlikely that the organism or construct we're examining is experiencing feelings, but we can never know for sure, no matter what philosophical machinery we develop for understanding qualia.
But this is nothing new. Recently it was announced that gravitational waves had finally been detected, stemming from the collision of two black holes over a billion years ago. The chain of inferences that rests on is mind-boggling. A more accurate statement would have been "In two separate places, specially constructed instruments registered a signal that indicated that test masses had moved, over a distance much less than the size of an atom, in a way that indicated that space-time had been distorted in a way consistent with the collision of two black holes over a billion light-years away. We feel confident about this because we believe that science works in general and we're convinced by a large web of observations and theoretical conclusions that the observable universe is billions of years old and billions of light-years in extent, black holes exist and, consistent with a distinct but overlapping web of observations and theoretical conclusions, in certain cases they should produce detectable gravitational waves. We have also done extensive measurements to convince ourselves that the detectors are in fact detecting gravitational waves and not just trucks driving by ..."
And that would be the short version. The full version fills textbooks and takes entire careers to grasp even a small portion of.
If science can accept that, can it come to accept that a dog is happy?
Not exactly. The sticking point here is not whether we can accept a long chain of inference like "People report feeling happy when certain neurons are firing in certain ways, they behave in certain ways when this is happening, dogs have analogous neural pathways, and these tend to fire when dogs are engaged in behavior analogous to that of happy people, and/or people report that the dogs seem happy." That's not a problem, particularly not compared to the detection of gravitational waves.
The problem is that science depends fundamentally on objective, repeatable measurements of numbers. Happiness is subjective, and happiness is not a number. Science can get quite close to measuring happiness, but it's up to us to decide where to go from there -- just like with any other scientific result.
