Companies come and go, expand and shrink, and some of the hopes they offer can quickly turn to ashes.

Amgen’s announcement that it will lay off 450 well-paid workers at its West Greenwich plant is a jarring reminder that no state or other jurisdiction should place too many eggs in one company or one sector.

Politicians and the general public love the big announcements that this or that big company may move in. Public officials provide many inducements in land, state and local services and tax breaks. Company executives promise a golden future, and for a while, economic-development-by-deal looks good (even as the costs of the inducements to one famous company are parceled out to the companies and taxpayers already in the jurisdiction, with unknown macro-economic effects to the wider area).

Politicians do not have a very good record in guessing which company or sector will thrive in coming years. But then, the world economy is far too complicated even for brilliant economists to predict that sort of thing with much accuracy. There are just too many variables.

No state or community should depend too much on enterprises whose needs and capacities may not long dovetail with those of the jurisdictions that try to attract them. And, in the end, senior company executives come and go at an accelerating rate, and even during their tenures, can quickly decide to close plants and fire employees with little or no warning. Employees are just figures on a sheet of paper, and public companies must please the heartless and impatient financial markets, which take the short-term view, quarter by quarter. (That’s bad for the country, but that’s another story . . .)

What a state like Rhode Island must do to prevent being hammered by the decisions of one company is to focus less on attracting individual firms and sectors and more on creating an overall climate for companies, large and small, already doing business here or considering coming here. That means a solid physical infrastructure, building on the state’s comparative advantages (which the state has disastrously failed to do with its international-port potential), good schools and a tax structure not less attractive to business than neighboring states’. (The paucity of graduates in the Ocean State with the skills needed for high-level 21st Century work is probably the problem most frequently cited by executives of companies in doing business in the state.)

Ignoring those requirements in favor of headline-grabbing deals with famous, glamorous individual companies and sectors is the road to economic disaster.

We’re very happy to have Amgen here — it’s a fine company. But no one company or a sector can be a solution for what ails Rhode Island — which includes an avoidance of economic reality.