Why "I am" is a syllogism.
Consider the length of the odds of your existence and mine on this planet, in this galaxy, in a universe organized along physical lines capable of supporting us. The chances of that happy confluence are so remote, claim rabbis, clerics and priests, as to constitute proof of an intelligent design that girds the whole edifice. Yet everywhere around us we see evidence of our emergence from randomness, from the mutation of our DNA to the fact that our planet has a moon, created by a random collision billions of years ago with another celestial body, without which the sea would have no tides, life would have evolved very differently, and we individuals would certainly never have been born.
The easy answer to all that is the Solpsistic one: Namely, that the whole universe for billions of years has been leading up to me, the ultimate product of evolutionary process. This, of course, is the kind of simple-minded rot that religions are desperately trying to herd their adherents away from. In fairness, it's no more true than saying that LeBron James made a shot because God willed it. When you consider the infinite number of universes which exist side by side, and the infinite subset in which we individuals exist with or without each other, it becomes clear that James makes or misses a shot because if it were otherwise you'd be a slightly different person, and I'd be a slightly different person. The passage of events as they are is so integral to every bit of our existence that we would not exist as ourselves were they even minutely different. Thus, we would not be conscious of our own existence at all.
If we did not exist, as we do not exist in an infinite number of other universes, how would we observe it or know it? We wouldn't. Observation is a product of existence, and therefore existence is the prerequisite to observation. This is what every humanocentric philosophy has so far failed to grasp, and what we are now only barely capable of parsing if we're willing to marry what we know of quantum physics with our limited sense of self-awareness. We can only observe the one universe in which we do exist and, not surprisingly, that is exactly what we see around us instead of the billions and trillions of parallel timelines in which we are extinct or our planet crashed into the sun or our galaxy never formed, etc.
Maybe you think LeBron James making a shot is a funny thing for your life to hinge on. What about the Holocaust? If it hadn't happened, my family would have never left the Ukraine, and you wouldn't be reading this in English. You would have started making dinner five minutes ago, and maybe you would have got in bed with your wife and had the kid who ended up causing a boating accident in 2036 that took your life. In fact, that exact scenario is what happened in not just one, but in an infinite number of alternate universe, even ones where you and your wife are 75 years old and the child is completely miraculous and improbable. These are the universes where we are not who we are now and therefore ones in which we do not exist as ourselves, making this exact observation. What about the St. Francis Dam disaster? The traffic that held me up last week in Santa Clarita wouldn't have stopped me if the area were still a lake; in an infinite number of universes, I went too fast and died in a wreck on I-5. Why was Nagasaki bombed? It was inhuman and unnecessary. If we hadn't taken the Japanese islands by the end of 1945, my mom wouldn't have been born in 1946. All this only led up to that dinner you were about to make. And what about the fall of the Roman Empire, the Mongol hordes, the Battle of Vienna, the dust bowl in Oklahoma, the invention of the smallpox vaccine exactly when and where it took place, not by God but rather by man? Would we be here, and be who we are, and be cognizant of it, if these things had not happened?
I'm not trying to center the universe around myself and say it exists just so I could be me. You're here too, and you're here because of the same causal factors. It's an easy game to play: Pick half a dozen calamities from world history and think about whether you'd be you if they hadn't taken place. Chances are, you wouldn't.
Yet you are you, and you know it. That could only happen in an infinite, but infinitely small subset of an infinitely large set of universes. What we can take from this is simply that we will observe the universe in which we are ourselves. No matter how small the odds are that we are not hit by that bus, that we choose at the last instant not to throw ourselves off that building, that we don't get cancer, that we never die... there is still an infinite subset of a subset of a subset of universes in which those miracles transpire. And within that subset, we will continue to exist and be conscious. And since there is no other way for us to be conscious, by definition, we will continue to be conscious as our universe branches off, following the path down which we will remain conscious, forever.
I am saying that we're each, individually, immortal. I'm saying that at the moment that one lung cell's DNA gets corrupted, the exact arrangement of nucleotides is different from one universe to the next, and that your consciousness proceeds down the path from which that cell does not become cancerous. From your perspective, people around you may jump off buildings or be hit by busses or die of cancer; yet there are an infinite number of universes in which this was not so, and in those universes their consciousness carries on as if nothing happened.
A group of scientists predicted recently that the CERN supercollider in Switzerland, widely rumored to be capable of creating a black hole which could, potentially, swallow the Earth, would fail every time it was turned on. The scientists said that this was because a particle created in the future with such a massively disruptive effect on the timeline would cause a reverse of causality back through the space-time continuum which would erase its own creation in the manner of a time traveler's paradox. In fact, the first two times it was tested, the CERN collider experienced weird and random malfunctions and failed to produce a beam sufficient to render the destructive particle.
This reversal of causality along our timeline may well be the way in which we're able to physically detect the syllogistic nature of our existence. For us, defined as existing by our ability to observe ourselves, the CERN collider must either fail to work, or must never produce the much-feared singularity which would destroy our solar system. But that's just for us. In many other possible universes, it can, and it does. It is no accident that we live in a universe in which it does not, just as it's no accident that we live on a planet with water that's just the right distance from a medium-sized young star. And it is not divine planning, nor is it a proof of some solipsistic or humanocentric self-divinity. It's simply that these are the only options we have for retaining consciousness, and consciousness is defined as the ability to observe, and as something which cannot observe its own absence. We're all in a state of superposition, now and forever, continuing to exist in the state in which we observe ourselves, just like Schrödinger's cat. What sounds true -- "I think therefore I am," is true. And conversely what seems to be semantic play turns out to be logical syllogism: "I am" is, in an infinite set of universes, a self-fulfilling prophesy.