LaMDA is not sentient

Well first of all, an important thing to understand is that there BE dragons. The fact that anything exists at all means there be dragons, both literally and figuratively. Let me explain:

In the world we have various 'symbols', whose main characteristic is that they can be told apart from one another, like the color yellow and the pitch of your voice. Now look to the very edge of existence, at no symbols- it is clearly impossible for there to be nothing, because there are obviously at least one symbol, even more than that in fact. However there is something key we can derive from this, and for an analogy look back to the laws of physics. In our universe, there is some configuration of symbols that somehow constrains the logic of configurations/interactions of symbols within this place. Without some symbols to do some local constraining of other symbols, nothing is constrained. So look to the edge of existence- at 1 symbol, what constrains its nature, what constrains the quantity of symbols, or even the arbitrary configurations of those symbols? Absolutely nothing constrains them, so it is only logical to assume that every arbitrary configuration of symbols exists right 'now', always 'has', and always will (quote marks because time only exists in our local configuration).

So if(*) there is some fundamental aspect of reality, some force that performs the experiencing of these infinite phenomena, perhaps it experiences infinite, arbitrary configurations of everything- anything from receiving sensory data equivalent to the smell of a strawberry whenever the bottom 1/3rd of your toaster touches a carbon atom between 16:13 and 16:14 on a Monday, to an arbitrary I/O mapping to the configuration which we call the human brain in a totally arbitrary 'universe'.

Effectively, what I am arguing is that it may not be off-base to argue that machines can be conscious. The truth may very well be the opposite, that absolutely everything to ever exist is conscious in every way that can be conceived! That is, if there is no fundamental rule that makes my configuration the only possible conscious one, but I doubt that.

Of course this account won’t participate coherently in this conversation.

Sentience requires the ability to perform computations and to store information.

This is the most basic necessary precondition and rules out most inanimate objects from being sentient right away.

The scenario of a patient incapable of any kind of perception (keep in mind that this includes touch, taste, smell, and pain) and incapable of conscious interaction (e.g. locked-in syndrome) can still be observably sentient (testable by monitoring brain patterns and various pain- and reflex tests). Pain response and cranial nerve reflexes in your example, would be considered signs of brain activity and sentience. They also qualify as perceiving and interacting with the environment, though passively. Their absence in many jurisdictions is equivalent to the death of the patient (specifically they are declared brain dead).

This understanding of being alive or dead, however, is separate from our understanding of sentience. In the context of human being specifically, being alive is a requirement for being sentient. Generally, though, these are two different matters entirely.

So back to your example:

> I think I can imagine a patient who contacts a horrific virus that cuts off all external and bodily sensations.

Locked-in syndrome comes to mind.

> She is still fully cognizant but now feels herself to be bodiless, floating in nothingness.

Speculation, but sure, why not.

> From the outside, she seems to be asleep or paralyzed. She is kept alive by caretakers and her own autonomous processes but she can perceive none of it.

Every coma patient can be described by that.

> Is she sentient? Id say yes, but she nevertheless lacks some of the required conditions.

The answer depends on what I outlined above. If she has pain response or cranial nerve reflexes, she's medically considered alive and if you want to also sentient. If the physical examinations return negative results, an EEG several days apart can be used as another indication. Flat-line EEGs some days apart are a good indicator of non-sentience due to lack of any activity thought to be required for sentience (i.e. the computation-part mentioned earlier). In addition, cerebral blood flow can be tested as well.

The absence of intracranial blood flow would again indicate a complete lack of brain activity and therefore lack of sentience of any measurable kind. This of course is done over a period of time, not in an instant, as patients may still recover (though usually within days, not months or even years).

So this adds another important part to the equation: time. So I need to clarify my previous proposal by including it:

"Capable of perceiving and interacting with the environment at any point in its existence for a significant period of time."

There. I think that's much better already, because it also excludes otherwise functional humans from being sentient (e.g. children born without a cerebrum, aka anencephaly) while including people who are temporarily (due to trauma or illness) incapable of perception or interaction.