I've said this a few times on this blog, but it bares repeating -- the universe is incomprehensible to the human mind. I came to this conclusion after my realization that all of human knowledge, revelation aside, is a direct result of the principle of cause and effect.
Human beings see effect B, and want to control it by finding cause A. In the physical world, we can isolate one effect and one cause and repeat the experiment until we are sure that A and only A causes B. That's science, and it's tremendously effective. However, even science cannot comprehend the world because the nature of cause and effect does not permit it.
A always causes B through some unseen mechanism. Let's use this notation A->B. We never understand the arrow. Even if you think you know something, like flipping a switch turns on a light (switch->light) that isn't the entire story. Flipping the switch sends current through the wires and allows the light to work. Switch->electricity->light. But that only creates two more unseen mechanisms, and creates two more questions. Why does flipping the switch allow electricity to run through the wires and how does electricity allow the light to work? This is why you always hear scientists saying that answering a question only created more questions. Of course it did. It creates two questions for every question answered because there are now two unseen, unknown mechanisms where previously there was only one. So, the physical universe is incomprehensible because two more questions are created each time a question is answered.
Our incomplete understanding doesn't matter in a great many cases. Just as a person does not need to know the intricacies of an internal combustion engine to drive a car, neither do engineers need to know every possible physical interaction to create a new technology. They only need to know the relevant ones. Yet, I've only addressed the physical world, when it comes to human interaction cause and effect cannot be so easily isolated.
Economics tries its damnedest to create theoretical models that isolate one aspect, ie cause and effect, within the economy. For example, David Ricardo explained why countries trade with each other, the effect, using comparative advantage, the cause. Subsequent economists have delved deeper and explained or discovered additional effects using new causes. Modern economists then use complicated mathematical tools, called econometrics, to determine if the cause and effect are correlated. Please note, even the most sophisticated of these tools only indicates correlation. In many cases, this is irrelevant because the proposed cause can logically only be the cause, and reverse causality can safely be omitted. However, in some cases, the proposed cause could itself be an effect of some third action that is causing both the proposed cause and proposed effect. C->A and C->B. A good example is flossing. I sometimes see statements that people who floss their teeth daily live longer. Therefore, flossing your teeth daily will add years to your life. In truth we see two effects -- daily flossing and longer life -- of another cause -- people following doctor's directions and generally caring about their health. Human beings and human interactions are not usually so easily explained.
Human motivations, ie causes, are so diverse and complicated that they cannot be isolated and determined to result in an action, ie effect. We can develop rules of thumb that people motivated by this or that will do this or that. Or even that people do X most of the time when they are in situation Y. However, we cannot predict who will do what every time. Maybe a team of shrinks could do it with enough time and background information, but I am more concerned about macro, societal level insight that can be used to create policy.
I find that insight from the accumulated wisdom of past generations passed down to us in the form of tradition. Societies aren't stupid. In fact, they would cease to exist, and therefore be unable to pass down traditions, if they were stupid. So, traditions have a proven track record in that they survived long enough to be passed down at all. With this in mind, I believe it is incumbent upon the people who want to break from tradition to prove one of two things. First, the circumstances where the tradition was created are no longer relevant. Since I believe that human nature is not particularly malleable, this is a tough case to make to me. Second, that the benefits of changing are greater than any reasonably foreseen costs. The costs and benefits are not quantifiable, and so, as most important decision, this is left open to judgement.
An important change currently debated in this country is same sex marriage. I'm sympathetic to the cause of gay marriage because I don't believe the change will have a drastic effect on society. However, arguments like Alan's about how marriage is simply a contract between two people and the government make me less sympathetic to the cause. Yes, Alan, your argument undermined my support for gay marriage.
You see, marriage should be a scared institution. A type of covenant toward your spouse and God. (If God bothers you, then with something higher thansimply the two individuals in the marriage -- society, Gaia, whatever.) Sure, the government can simply think of it as a contract because governments enforce contracts, but that does not mean that we devalue marriage to a simple contract in order to justify gay marriage. That is a myopic, expedient why to argue in favor of gay marriage. I would be much more comfortable arguing that a strong covenant would benefit homosexual couples as much as heterosexual couples. I believe the effect of devaluing marriage to legal contract is without a doubt more dangerous than allowing same sex marriage. And yes, I know that quickie divorce and other, shall we say, progress has gone pretty damn far towards making marriage only a contract, but I still say we should fight any further devaluation of marriage at all costs.
In any case, the innate human method of understanding the world, cause and effect, renders the world, both physical and human, incomprehensible.