When in doubt, use a stronger glue to build stronger bonds. This is because it’s easier to add the extra glue than it is to clean up the mess and start over again.

Imagine you’re building a house. You want to save money on glue, so you buy crappy bricks and glue them together with water. The house looks good while it’s still wet, but after it dries, the bricks fall apart, because the water evaporates into thin air.

So you go back to the store and buy some stronger glue to repair your house. But no matter how much better this new glue is compared with water, it can only do so much because it has to adhere to your crappy bricks, which were built from bad mortar and sand.

To fix this problem, you need more than just better glue; you need better bricks too! So you go back to the store and buy some new bricks that are made with a secret formula (i.e., better materials) by world-class brick makers (i.e., master craftsmen). Then when those shiny new bricks meet at their edges, they form an atomic bond with each other and become one single unit of strength that will outlast even the strongest storm or earthquake or flood for centuries upon centuries

When in doubt, use a stronger glue.

This is good advice. But it has one flaw: it can be hard to know when you’re in doubt. A lot of the time you won’t realize that you need more strength until after things have broken. Then it’s too late.

So how do you tell when you’re in doubt?

The way to tell if you’re in doubt is if you think about how much money something is worth, or how long it will take. The problem with these questions is that they’re backward looking and based on past experience. If you are building something for the first time, or trying to do something that hasn’t been done before, then it’s very difficult to answer them accurately. That doesn’t mean that they aren’t good questions; they just aren’t good ones for figuring out whether or not you’re in doubt.

The right question to ask yourself is: “What would happen if I did this ten times?” If the answer isn’t obvious, then you should use a stronger glue.

A common error is to use a glue that is too weak for the job. For example, if you were building a house out of toothpicks, and wanted to glue them together, you wouldn’t use a dab of saliva on each joint. That would be a bad mistake. Everything would fall apart as soon as it dried. If you want something to stay stuck together, you need a strong glue.

The same is true in business, except that in business the things you want to stick together aren’t made of wood. They’re made of people. People come with their own glue: they call it loyalty. But unlike most natural glues, loyalty doesn’t get stronger when you add more of it. Once the necessary minimum strength is achieved, adding more won’t help.

So when in doubt, use more glue? No; that’s still not right. Because the properties of the materials being glued are different from the properties of wood. A better way to build things out of people would be to find the weakest link, and strengthen that first.

How do you build an adhesive cement? You could make a strong glue, but then you would have to keep it in a tube. You want something you can paint on.

So the first thing to try is a solvent: dissolve the glue and use that. But glues are polymers, long chains of atoms all stuck together. To dissolve them, you need a solvent that will dissolve the individual atoms while leaving the chains intact—which is hard. If you want your cement to work underwater, forget it: no solvent will work in water.

Water-soluble glues like Elmer’s are weak because they are actually just suspending the glue particles in water; there is no chemical bonding between them and the surface of what you’re gluing.

The solution is to put another chemical in with your glue: one that will react with it chemically, getting into its structure and still allowing it to form a network. The result is a polymer resin, which is both soluble in solvents and has very strong intermolecular forces within itself. That’s why epoxy glues are so strong: each molecule really does bond to the next one.

A few years ago a friend of mine was taking a flying lesson. The instructor, who was a very experienced pilot, let him take the controls and had him climb to 1500 feet. Then he said “Now I want you to turn the plane upside down.”

My friend replied, “I’d really rather not.”

The instructor assured him that it was quite safe; they were in a Cessna 152, one of the most forgiving planes in the world. My friend said no a couple more times, but the instructor insisted. Finally my friend gave in and turned the plane upside down.

Then he panicked and started flailing at the controls. The wings shook, and he couldn’t see anything out the windows except sky. After about half a minute of this he managed to flip the plane back over again. He looked at the instructor accusingly and said “That wasn’t very nice!”

“Maybe not,” said the instructor calmly, “but it sure did cement our relationship.”

The most effective way to solve problems is not just to think about it, but to do something about it. A person who is constantly solving problems is bound to find new opportunities. The same can be said for a business. A successful business solves people’s problems. If you do it well enough, you’ll create your own opportunities.

We were working on a way to make software for mobile phones that would help people get information and communicate more easily. At the time, we were thinking about how to adapt our existing products from the desktop into the mobile environment. We discovered that while there was some demand for basic applications like email, Internet access and games, there wasn’t anything that really helped people get things done on their phones or made their lives better (in other words, not just mobile versions of our desktop products). To figure out what would be useful, we went out and talked to customers to see what they needed most. After many customer visits and lots of research, we found that people really wanted a way to stay in touch with what was going on in their personal lives (like keeping up with family and friends) as well as the latest news headlines and sports scores.

We realized that what people wanted was a mobile service that kept them connected. But we also

A few years ago I was visiting MIT, and I ran into a friend who was then a professor there. He was working in an obscure corner of psychology, on how people make moral judgments. His lab setup was charmingly low-tech: he had subjects sit at a table opposite each other, and made them play a game with money.

I asked him what he’d learned so far. He said that on the whole it seemed like people were more trustworthy than they thought they were. They would agree to play the game again sometime, and almost always they did.

Then I asked him how many times people had broken their word. The answer was none. Not one person had failed to show up for a second game when they’d agreed to. The next question was obvious: well then, what’s the point of this experiment? If everyone does what they say, you’ll never learn anything about trustworthiness by doing this!

And he said “Yeah, I guess if I’d been smarter I would have realized that.”