So I'm going back to the thinking of Aristotle again for my next philosophy. Aristotle claimed that everything in the universe with proper structure also had proper function. You cannot build a chair correctly without it functioning as a chair and you cannot build a shelter correctly without it functioning as a shelter. If you build a chair poorly, it will function poorly and if you build a house poorly it will once again function poorly. Structure and function therefore have a direct correlation. One affects the other. Now his examples were primitive compared to our standards and I know that you immediately began brainstorming things that can have structure without function that exist today. Rest assure, everything that has proper structure has proper function. Aristotle's claim still is true today. One of the examples you may have gave to counter his claim is a light bulb. It's function is to light up, and you can make a light bulb but that does not mean it will light up because it can't without electricity. However, you would be missing the actual function of a light bulb which is to allow electricity to flow through it. The electricity's function is to produce light, but I've digressed enough.
You are probably wondering what structure and function have to do with the title of this note, soul. Well it is actually our advancements in technology that prove the existence of some sort of soul. The human body's function is to live and it is also structured to do so. The human body is so fascinating in the sense that it has so many mechanisms to sustain life. Its ability to regenerate from injury and operate under strenuous conditions is impressive. However, eventually the human body can no longer perform its function. This is death. However, people can die with perfect structure. With modern medical technology, you can take a corpse, hook it up to several machines, and have it pump blood, force the lungs to breath, get the heart beating again, and even get blood to circulate to the brain. Yet, even though all these process that usually take place in a live body are being performed, the person is still dead. The body has its proper structure, but lacks its proper function. This phenomena implies that there is a structure to the body that is destroyed that we cannot fix and that we cannot see. It has no relation to the biological aspects of the body. This would be the soul. Not the spiritual soul that you are probably thinking about, I'm not saying your soul dies when you die (that's up to your own beliefs), but when I say soul I mean more like psyche. The fact that a human body can have all its biological aspects and still not be alive forces the notion that the body is more than just flesh and blood. There is an intangible part of the body that has the same amount of influence over the body's function as the physical aspects of the body. In addition, since we have already established that everything with structure has function, than the fact that the human soul has influence over the human body's function implies that the soul has structure. Not concrete physical structure of course, but structure in the sense that there is something about the soul, or psyche, that can be injured or destroyed that is unrelated to the physical structures in the brain or body.
If you take this philosophy to heart, you'll understand that when people don't die of old age it isn't by chance. The day that person died is not random. Something happened to their "soul" that day at that particular time that disrupted its structure. People always talk about how in a hundred years technology will be so amazing that people will live so many more years than they do now, but at some point medical technology will only be able to keep people alive for so long. The physical components of the body will be perfectly healthy, but the "soul" will deteriorate. Until science can explain the phenomena of the soul, immortality, or near immortality, will always be out of reach.