So mainly he figures he's in a coma, and his mind is inventing everything around him for some purpose. And if he can divine that purpose, he will somehow be able to come out of his coma. He tries but is held back from committing out and out suicide in the first episode; figuring that killing himself–or at least acknowledging that this world (1973) is an illusion and fully committing to it by killing himself–will shatter the illusion and bring him back to the real world. But he's not really sure. Possibly, killing himself inside the coma would also kill him in the real world. Again, sounding familiar?
The lesson he is told by the wise bartender character in that episode, and which gets repeated throughout the series is that he must make the best of where he is; make a difference in the present whether or not it is an illusion. And maybe it's just the way that the show is done, through layers of consciousness/unconsciousness/dreaming that resonates with me (as that's my personal area of interest/expertise), but I really like that that's the message. Because that's really how I feel about life. You can never know if you're really here, or just in Plato's Cave, or even what "really" and "here" mean. Maybe it's a solipsistic universe, maybe there's a god or maybe there isn't, or maybe it's some Gnostic illusion like Linklater talks about at the end of Waking Life. All you can do is operate on the information you have at present to do the most good that you can for the people around you.
I used to get myself tied up into knots thinking about morality. What if you save someone's life, only for them to shoot someone later? But you can't control the outcome of your actions; you can only control your actions, and the intent behind your actions.
Another reason the show resonates for me didn't become clear until the finale. As Sam becomes more and more sure that he's comatose, I got the sense that he was moving towards a sort of invincibility. So many people spend their entire lives in fear of death. When it looked like Sam was starting to act without regard for his own life, I cheered a bit. Because that's what heroes are made of. Most people view their own lives as the most precious thing in the world, and so stop short of sacrificing themselves to stop an injustice. Which is not really illogical, when you think about it. Again, why trade your life for a stranger's? Especially when that person may themselves be a murderer, or a thief, or a liar. But true heroism is born when you let go of that conceit: that you are somehow entitled to your own life, even at the cost of someone else's.
Of course, Sam's apparently fearlessness is really just brashness. The last two episodes of the first series show how his motivations are ultimately selfish, despite all his white-knighting (and as his boss puts it, his "holier-than-thou" attitude). I've been there. And this is what undoes him in the final episode. He can't do the one thing he must. He confronts his father, but cannot arrest him. He accepts his father's criminal past, but still feels the need to protect his childhood and his mother. It's not an ignoble gesture, but it's ultimately a false one. In denying the reality, he closes off the reality of his life in 2006. The sounds of the heart monitor in his hospital room are the loudest as his father asks to be cuffed, and fade as he lets his dad walk away. But not all is lost; he's saved Annie from a savage beating (and possible murder), but who knows who his father will hurt in the future?
Again, we can't always see the consequences of our actions, but none of us are perfect. This finale was an excellent example of thoughtful drama. It was not cut-and-dried, but it was not exactly ambiguous. Every first year film student talks about how brilliant complex endings without black-and-white resolutions are, but in this case, it is pretty clear to us in the audience what happened while still remaining opaque to the character. That's a really important and fine line to tread. We all blind ourselves to the input from our senses on a daily basis for one reason or another. But again, we do the best we can with the info we have.
And maybe it's not completely opaque to Sam Tyler. We make mistakes so that we may learn from them. Hopefully, Sam learns something from this he can put to use in Series 2. And maybe we can all remember to embrace the moment, live as if we're dreaming, and do the best we can in the situation we find ourselves.