Ideas don't move through history by themselves. They need something to carry them.

A religious teaching needs language, teachers and eventually institutions. A political principle may become a constitution, a law or a court decision. Scientific knowledge moves through universities, journals, laboratories and textbooks. Even a family story needs someone to keep telling it.

The interesting part is what happens along the way. We sometimes talk about an idea as though there were a clean version somewhere outside the world and a corrupted version after human beings got involved, but I'm not sure the clean version ever existed. An idea that can't be communicated, interpreted or acted upon may be an idea, but it isn't doing much yet. Eventually somebody has to give it a form, and that introduces constraints.

Consider a simple principle like equality. It sounds reasonably complete until we try to enact it. Equal in what sense, and before which institutions? Does equality require treating everyone identically, or can different treatment sometimes be necessary to produce equal standing? Who decides, and what happens when equality conflicts with another principle we also value?

The moment the principle enters the world, people have to start answering questions that weren't contained in the word itself. Now the idea has acquired a history, and that history matters because later generations don't inherit the original idea alone. They inherit previous attempts to put it into practice.

The American founding provides an unusually visible example. The language of equality appeared alongside slavery. That contradiction didn't make the language meaningless; people later used the stated principle to challenge institutions that violated it. It also didn't make the contradiction imaginary. Both traveled forward.

A principle can constrain the institution carrying it even when the institution fails to live up to the principle, and the reverse can happen too. An institution can gradually change what people understand the principle to mean. Constitutions are interpreted. Religious traditions develop schools and doctrines. Scientific institutions decide what counts as evidence. Political movements discover which arguments attract supporters.

Sometimes those changes are corruptions. Sometimes they're improvements. Sometimes they're adaptations necessary for an idea to survive circumstances its original advocates never encountered. Usually the interesting cases contain some combination of all three, which makes historical inheritance difficult to judge from a single moment.

Take an institution that compromises in order to survive. From one position, the compromise may look like practical wisdom. From another, it may look like abandonment of the thing the institution was supposed to preserve. Both interpretations might even become more or less convincing with time because we get to see consequences the people making the original decision couldn't. They had to act without them.

This is why I'm increasingly interested in the distance between what an institution says and what it actually does, although not because every difference proves hypocrisy. Sometimes it does. Other times the difference tells us that the principle was incomplete, the circumstances changed, two legitimate obligations collided, or the available institution simply couldn't carry everything people were asking it to carry.

The gap is information.

A newspaper can say it serves its community, but that claim doesn't establish that it does. You can look at what it covers, who can reach it, what happens when it makes a mistake, whether the institution changes when the community changes, and whether its behavior still resembles the reason people trusted it in the first place.

The same test works surprisingly well on much larger institutions. What does the constitution say, and what does the government do? What does the religion teach, and what does the institution reward? What does the company promise, and what happens to employees and customers when those promises become expensive? The distance between statement and behavior gives us something concrete to inspect.

It also protects us from an easy mistake in the other direction. Sometimes we become so interested in exposing contradiction that contradiction itself becomes the conclusion. A founding principle was violated, therefore the principle was fraudulent. A religious institution behaved badly, therefore the teaching was only a tool of power. A reform produced unintended consequences, therefore the reformers were secretly pursuing those consequences all along.

History rarely gives us that much access to motive. More importantly, those conclusions can cause us to throw away information. If people repeatedly appeal to a principle when challenging the institution that claims to represent it, the principle is still doing something. Perhaps the institution didn't merely use the symbol. Perhaps the symbol also placed a constraint on the institution.

That relationship can persist for a very long time. A society says people are equal while maintaining institutions that obviously treat them unequally. Someone eventually asks the annoying question: If we believe this, why are we doing that?

Now the old language becomes leverage against the system that inherited it. The contradiction carries information forward, which doesn't mean contradictions are secretly good. Some contradictions destroy people while everyone else waits for the institution to notice. It means concealing them costs us something else: the ability to compare what we're doing with what we say we're doing.

Once that comparison becomes socially or institutionally impossible, adaptation becomes harder. Everything has to be explained as consistency. Old decisions acquire new justifications, exceptions become precedents, and temporary compromises become traditions. Eventually people inherit a system without knowing which parts were principles and which parts were accommodations made by people facing circumstances that no longer exist.

This isn't unique to governments or religions. Organizations do it. Families do it. Software does it.

Someone makes a strange decision twenty years ago because of a problem that existed at the time. The original people leave and the problem disappears, but the decision remains. Eventually someone asks why the system works that way and gets the familiar answer: “That's how we've always done it.”

Now the history of a constraint has been mistaken for the constraint itself. Sometimes the right response is to remove it. Sometimes you discover that the strange old rule was protecting against something you've forgotten. So you investigate before deleting it.

Ideas deserve the same courtesy.

We inherit principles through forms built by people who were solving problems under conditions different from ours. Some of those forms still carry the principle well. Some have drifted. Some contain compromises that became invisible through repetition. We don't have to choose between worshiping the inherited form and discarding it.

We can ask what they were trying to preserve, what they actually built and what happened afterward. Then we can look at what has changed since, what still works, what doesn't, and what we might accidentally destroy because we've mistaken an old vessel for the thing it was carrying.

There won't always be a clean answer, and that's probably appropriate. The vessel changes the idea, while the idea can also change the vessel.

What reaches us is the history of both.