Since childhood, we have been hearing from Joe public (not to be confused with Joe the plumber) how things are "impossible". People all the time claim to be authorities on possibilities, yet are completely ignorant as to the factors involved in making that bold assumption. Conversely, we pay motivational speakers and gurus big bucks to tell us that "nothing is impossible" if you put your mind to it -- and if you sign up for their next seminar. So what actually is impossible, if anything? Is the concept of impossibility just some subjective idea or does the impossible have some objective existence that can't be overcome with any amount of brain power, might, prayer, and/or time? And what does this mean for how we live today?
Let's begin by looking more closely at the term "impossible". It should come as no surprise that most people use this term incorrectly. Think about the times you heard this term used. The chances are, it was used in such a way to convey emotion for something difficult or improbable. "This homework is impossible!" No, unless you have a cruel teacher, it's most probably not. "Driving 10 blocks in the city without hitting a red light? That's impossible!" No, just unlikely.
There are actually different kinds of impossibilities, and depending on who you ask, these can go by different names and be categorized differently, but the main concept is that varying degrees of impossibilities exist. Here is my attempt to categorize these.
Statistical impossibility. Imagine filling a dump truck with over 1 million fair dice (six-sided, weight evenly-distributed). Now imagine dumping all those dice on a huge Monopoly board. Would it be impossible for all 1 mission dice to turn up as ones? In a sense, YES. We call this a statistical impossibility because it is so improbable, that in all practical terms, it is impossible. Notice that is a subjective definition -- there is no objectively defined point where something is just "very improbable" then becomes statistically impossible. The second law of thermodynamics falls into this category. While we say that it is impossible that all the oxygen molecules in the room you are in right now will spontaneously collect in one corner of the room, causing you to die of hypoxia, it is more precisely statistically impossible, or very, very improbable.
Physical impossibility. This is something that defies the physical laws of nature as we now understand them. Science is an every-changing field with new rules, new exceptions to existing rules, and even brand new branches appearing that dramatically change our understanding of the natural world and turn the once impossible into possible. As Lord Kelvin once said, "Heavier than air flying machines are impossible." At the time, according to the known laws of nature, he was describing what was a physical impossibility. But the Wright brothers never got that memo, and sparked the scientific community to re-examine the laws after they apparently defied them. It is impossible to reverse gravity and cause levitation? Is it possible to move object with only our minds? Is it impossible for humans to instantly teleport to another part of world? In all practical terms, yes -- these are examples of physical impossibilities. But this does not mean that some day, no matter how improbable, the laws we know will be better understood to make these things possible.
Absolute/Logical/Mathematical impossibility. In "Think and Grow Rich" old timer Napoleon Hill's tells a story about a time when he was publicly presented with a dictionary as a gift. He refused to accept the dictionary until he ripped out the page with the word "impossible" on it. His motto is "Whatever the mind can conceive and believe, it can achieve." Powerful words, and not a bad motto to adopt, but what about those things that mind cannot conceive? Like a married bachelor? A three sided square? I bet you wish you hadn't defaced your dictionary now, Mr. Hill. These are examples of logical impossibilities that by definition are impossible. Can it ever be colder than 0 Kelvin, or absolute zero? No, it is an absolute impossibility. Can 1+1 ever equal 3? No. It is a mathematical impossibility. These are things that are not based on probability, nor dependent on our understanding of the laws of nature. These are unchanging impossibilities.
Paradoxical impossibility. We use colorful language to describe ideas that exist in our minds, however not all these ideas translate to a possible reality. Theists like to say that God is omnipotent, or all-powerful (even though the Bible never says this, and many stories in the Bible clearly demonstrate the limits to his power). But once you imagine a being creating a rock so heavy that he cannot lift it, the paradox kicks in and we have a paradoxical impossibility. The co-existence of an immovable object and an unstoppable force, saying "I always lie" and meaning it, or other uses of absolute terms that leave no room for exception, often create these impossible paradoxes. Perhaps a God exists who is just very powerful, an object extremely difficult to move and an extremely powerful force, and someone who lies virtually all the time. When we ignore limits in nature and logic, we create impossible paradoxes.
How can knowing this help us to live better lives? Simply being mentally aware of the impossible opens up of the world of possibilities. You begin to avoid the word "impossible" in everyday conversation, and use more accurate terms such as "highly unlikely" or "extremely difficult" that leave room for possibility in your mind and in the minds of those over whom you have influence. This open-mindedness helps you to better understand reality which ultimately results in better decision making.