Consciousness

[Alan V]

So if there is only one kind of substance, then is that substance conscious or non-conscious?

Consciousness is not a substance because it is abstract information processing.  It is both virtual and entirely brain-dependent.  

Biosemiotics is the study of how biology can encode information.  DNA is one example, but consciousness is another.  You are reifying consciousness.

We only have evidence of the experiential.

We have evidence of both the experiential and the physical.  As you pointed out, that is a problem.

But life can be explained in terms of non living parts. But subjective experience can't be explained in terms of non-subjective experience. Life from non-life isn't radical in terms of its emergence. Consciousness from non-consciousness is radical.

As I mentioned, consciousness did not emerge from non-living matter but from life.  Consciousness evolved gradually, along with life, from lesser forms of subjective experiences.

Again, we can explain life in terms of things that are not alive. But we can't explain consciousness in terms of things that are not conscious.

Perhaps you and I can't, but scientists are making great progress in understanding consciousness.  See this post about the progress that scientists are making.

Life doesn't have a use for consciousness either. We could react as if we were in pain, for instance, without actually having to feel it.

It's thought by some scientists that to store all possible reactions to circumstances in our brains would take much larger brains.  So consciousness evolved as an economical shortcut, a way to improvise reactions based on perceived circumstances.  In other words, just because something might be possible doesn't mean that was the way we evolved.

The consciousness emerges from the brain which is consciousness-involving. And just because we don't remember being conscious isn't evidence that we weren't or aren't conscious.

The brain activity which underlies consciousness is not in evidence when we are in deep sleep, in a coma, or under an anesthetic.  Consciousness has signatures, which are discussed in the link I just gave you.

You really do need to read about consciousness research.  The time has passed when philosophers could merely speculate on such issues, and their ideas were just as good as anyone else's.