Informal statements are often imprecise. Consider these two statements: “I have just finished dinner” and “I will always love you”. Both are imprecise. Why? Because both are certain about one thing, and leave out many possibilities. My memory is imperfect. My feeling could deceive me. I might have thought about yesterday experience while in fact haven’t had today’s dinner yet. My feeling of full in my stomach could be caused by the water I drank. But these possibilities are very unlikely, consider I’m of a sound mind and I’m usually able to distinguish between the feeling of full caused by food and that caused by water.
So, what would be the precise statements? Of those two mentioned, the precise ones can be: “I’m quite certain (there is a high probability) that I have just finished dinner” and “There is a chance that I will always love you”. About recent past event, I’m quite sure. About distant past event, I’m less certain. The same is about the future. So, considering the chance that “I will always love you”, if I ever say that to my future lover, I think it is quite low. Why? No matter how much I know about myself and no matter how confident I am in my love, there many things outside of my control. I can’t control what my lover thinks and how she may change in the future. I can’t control external circumstances, the development of future technologies, some of which may radically affect me, my lover or our relationship. For normal people, illness, family issues and change of place or job could be enough of a reason for a change of mind. Even if I’m confident that I won’t be affected by these factors, there are many unknown possibilities which I haven’t thought of. What if she merges her consciousness with a computer and becomes a totally different person (or thing), who perceives the world in a totally unimaginable way? What if we can control aging and be young forever? Or maybe just slow down the aging process, so both can live 500 years? Don’t think it is too far-fetched. I’m sure most lovers 50 years ago would not able to imagine that today lovers can live thousand miles apart and communicate mainly via a network of computers called the Internet.
Therefore, statements about the future, especially about things outside of our control, should be given carefully or taken less seriously. However, in normal situations, optimistic/approximate statements are usually acceptable, for 2 reasons. First, because the informal context doesn’t require precision, and precise statements are lengthy and even ridiculous (“Will you visit me tomorrow?” “There is a high probability that I will, considering that currently I’m of good health and there is a low probability of traffic accident”). Second, optimistic statements say something about the believe and commitment of the speaker. “I will always love you” could mean “I will try my best to be reliable, to love you as I currently do” or “I believe that my love for you will last”. Thus, it is totally okay to make such statements in normal circumstances. Yet it is another thing to believe literally what those mean. The latter is called blindness and stupidity. Well, you can say “I know all that, but I prefer to be blind and stupid and follow my emotion and impulse”. I can accept that, as long as you realize you are being irrational. But there are people who don’t even know that they are being stupid and irrational. There is one who even blamed me for being unreliable when I refused to make precise statement regarding what I would do and where I would be after 5 years. Thinking about those always makes me marvel at the limitless of human ignorance.