Hard Isn’t Tough
Diamond is the hardest natural material on Earth. Nothing scratches it except another diamond.
Hit one with a hammer and it shatters.
That isn’t a flaw in the diamond. It’s a flaw in our vocabulary. In everyday English, hard, tough and strong are near enough the same word. To an engineer they’re three different questions:
Hard: how well does the surface resist being scratched or dented?
Tough: how much punishment can it absorb before it cracks?
Strong: how much load can it carry before it bends for good or breaks?
Diamond aces the first and fails the second. Glass is the same: hard enough to scratch steel, and in pieces after one bad bounce. A car tyre is the opposite. It’s soft enough to dent with your thumb, and it takes thousands of kilometres of potholes without complaint.
Then there’s titanium, the metal with the best press agent in the periodic table. It’s genuinely strong for its weight, and tough. It’s in jet engines, hip replacements and the frames of very expensive bicycles. So surely it makes a magnificent kitchen knife?
It makes a terrible one. Knife steel is measured for hardness on the Rockwell C scale, and a good kitchen knife sits around 58 to 62. The common aerospace titanium alloy sits in the mid-30s, and even special heat-treated titanium only gets into the 40s. It’s too soft to hold an edge. The main reason anyone makes a titanium knife is that it won’t rust, which is why you’ll find them on divers’ belts, not in chefs’ kitchens.
The old words knew this. Tough comes from the Old English tōh: tenacious, sticky, holding together. Toughness was never about being impenetrable. It was about not coming apart. Hard, meanwhile, already meant severe and unyielding a thousand years ago. Neither word has changed its job. We just stopped telling them apart.
Which brings me to leadership, where we use all three as compliments without noticing they describe different people.
The hard manager is all surface resistance. Criticism doesn’t scratch them. Neither does new information. They hold their shape beautifully, right up until something hits them at the wrong angle, and then they shatter, often taking a team with them.
The tough manager takes the blow, gives a little, and holds together. They can be dented. They bounce back. That’s the person you want when the year goes sideways.
The strong manager carries the load. It’s the least glamorous of the three and the most useful.
Organisations constantly hire for “tough”, promote “hard”, and act surprised when the shiniest thing in the room turns out to be the most brittle.
Diamond is a wonderful material for cutting things, and for sitting in a ring being admired. Just don’t build anything that has to take a hit out of it.
