I'd like to know what kind of action is most beneficial to me, but first I have to back up a little and consider if I am more than a merely material being. I've written a couple of essays on why I am more than mere matter and now I'd like to go back to logic to consider the question. Logic informs me that A=A and that ~A= ~A. As obviously true as these statements are, they are nothing but rules in a game called logic that has nothing to do with reality. Of course A=A. Who can deny it? However, reality is in constant motion and changes from one instant to the next. If we consider time 1 and then time 2, we can say with certainty that A at T1 does not equal what we call A at T2. No matter how close T1 and T2 are in time, the thing we called A will have gone through millions of changes by T2.
The mind's trick, then, is to equate A with not A. In many cases, this is a simple and natural process. The glass that sits before me doesn't move or visibly change even though I understand that it is composed of a slowly flowing liquid. It is natural for me to say glass A is glass A. But when I move to more complicated ideas such as plants, I run into a substantial problem. I can't tell the difference between the seedlings of tomatoes and the seedlings of weeds. By nearly all objective standards, the seedlings of the different plants are more similar than the seedlings are to their adult forms. Nevertheless, I equate seedling A with adult form A. It serves my purposes to do so. In general, I equate A with not A when it is USEFUL for me to do so. I abstract out some similarity (or perceived similarity) and give it great weight by giving it a name e.g."tomato plant." I might also abstract out some other feature of a being and give it great weight. For instance, I might speak of poisonous and nonpoisonous plants. This distinction does not correlate with genetic similarity.
Words were created on the basis of utility not real identity or objective similarity. Wouldn't I be foolish to accept the words that other people try to force on me if they don't serve my purposes? If you ask how people can disagree on seemingly simple points, you should look into the words they use and what those words mean to the speaker. It's also important to ask what use the words have to different people. A simple example is the debate on evolution. Complicated political and scientific debates may be charged with the same sort of emotions that characterize the evolution debate even though the debaters are adept at hiding their agendas.
What happens when we turn our philosophy or science inward? I at T1 am not I at T2. This leads to a rather curious state of affairs. The beneficiary of my actions is someone else. Why should I bother to do anything that isn't immediately gratifying? Many people refuse to do things that will benefit them in 20 years, but why do anything that will benefit you in 20 seconds? Or 1/20th of a second? As with the question of sense impressions and memory, I am at a dead end. In order to continue, I have to postulate my own identity. Far from being a natural or logical postulate, the postulate of my own identity is highly questionable. I don't even remember anything before I was 3 and very little after that. When I was younger, I heard someone claim that every sense impression we ever had is locked in our brains. Many people believe this without question, but there is obviously no proof of it or even evidence that it might be true. It may be that a major function of the brain is to erase sense impressions. Who knows? Maybe my memories are all false and I am stumbling foolishly about an alien world with my memories changing from second to second creating the the instantaneous illusion that I have a coherent history. Then the history changes in the next second.
I explored an even more bizarre idea in my essay "Hearing Voices." The postulate of identity requires that I am a single being, an individual. The problem is that I am obviously not unified internally. We have the expression "I am of two minds," but that hardly indicates the depth of the problem. Let's look at a simple sentence, "I decided (to try) to cut the lawn before dinner." I throw in the (to try) because I can't decide to do anything. What is the origin of the decision? Must there not have been some internal debate that is now masked by the simplicity of the sentence? To decide, to will, to try, in fact, most mental activity implies conflict. St. Paul sees the conflict as spiritual in nature, "For we know that the law is spiritual: but I am carnal, sold under sin. For that which I do, I allow not: for what I would, that I do not; but what I hate, that do I." He divides the individual into two parts, the flesh and the spirit; but why limit the division to two parts? Aren't there many voices speaking from us? I know nothing about artificial intelligence, but I have a suggestion. I know that scientists are experimenting with neural net setups; they might try to create competing soft or hardware within the system. Such a computer may not be useful for many applications but it may give a more perfect imitation of the human mind.
I can't think of a more useful postulate than the one of my own individual identity. If another way of looking at myself is more useful to me, I'll give it a try. But for now, I take as a fundamental axiom that I have a continuing identity. Since A never equals A over time in the material world, this identity is non-physical.