Most Helpful Guy
When you promise something to someone, you’re taking personal responsibility on the outcome of your word. You are basing what you’re promising to do on the value of your word, which is why in ancient times when a person’s word meant something, very few people actually would make such a vow/promise, because if they did not uphold such a claim then the value of their word was no longer trusted, and they would not be counted on as leaders or commanders of other men. You could not be a leader of men if you’re word had no value or was no respected, because you never adhered to your word in strict adherence to the customs and society at the time.
When you swear, you’re swearing on something. Such as how it use to be in the United States, you would be your hand on the Christian Bible before testifying, because you were “swearing” by this book, this Holy Book and by God you would tell the truth. You’re holding or saying someone beyond yourself is held accountable for your actions or through such higher authority you will abide by your word, because if you did not then by that which you swore would be affected. Such as, “I swear on the lives on my children” you’ll do something and if you failed then in like manner, the lives of your children would be forfeit.
In retrospect, I would like to also comment on the fact a person should never “swear” to do something or by something, because since we did not create the items we swear by, we therefore, in some philosophical teachings, should never swear by things we did not create. Like we should not swear on the lives of our children, because we did not create them, we only helped give birth to them. God actually created them. We should not swear by God since we have no authority over him, as he made us, and therefore, we don’t hold such power to swear by it as if to affirm we’ll abide by the word we give to complete or accomplish a task.
This is now getting into the realm of a philosophical debate and one I’ve had many times with colleagues, but you should be able to understand the basic principle of what I’m explaining between making a promise and swearing by something. A promise is something you say you’ll do and a swear is you’re swearing by something or someone you’ll do something instead. That’s my bottom line.