When confronted with a deadly force that could threaten your existence, it’s crucial to know as much as you can about the force before you respond. You can’t outrun a bear, for example, but shouting and pepper spray are likely to scare it away. Running from a bear could get you killed.

Maybe the same could be said about heroin and opioids. More knowledge about this scourge might help shape a more effective response to eradicate it.

The opioid epidemic, which contributed to a record 47,500 overdose deaths in the United States in 2014, began as a business decision by a Mexican drug cartel anticipating a huge loss of profits from declining marijuana sales.

That’s the conclusion of best-selling author Don Winslow in a feature article he wrote for the Aug. 9 edition of Esquire.

Winslow, who has followed the Mexican drug trade for nearly 30 years, points to the gradual acceptance of marijuana in the United States.

“We wanted legal weed, and for the most part, we got it,” Winslow writes. “Four states have legalized it outright, others have decriminalized it, and in many jurisdictions police refuse to enforce the laws that are on the books, creating a de facto street legalization.”

Suddenly the Dominant Sinaloa Cartel, headed by Joaquín Guzmán Loera — el Chapo — found itself in competition with American marijuana of superior quality and lower price, and without the logistical challenges of an illegal border crossing.

In other words, there was no longer any way for the Sinaloa Cartel to make money selling pot in America. So Guzmán came up with a brilliant business plan: replacing Mexico’s marijuana fields with opium poppies; hiring Colombian technicians to purify the opium into heroin; flooding the market with it; and dramatically lowering the price — just as Americans were awakening to a growing problem with the addictive painkiller OxyContin.

There were two other key element in Guzmán’s strategy.

The first was eliminating competition. Winslow’s account includes details of ruthless killings and government corruption, both intended to silence opposition.

Guzmán has been captured and thrown in prison twice, but both times he has managed to escape high-security prisons — allowed to escape, Winslow contends, because he is the only one who can keep the peace between rival cartels beneath the Sinaloas. His release implies the power he holds while controlling an estimated 8 percent of Mexico’s total economy.

The second element was fentanyl. The Sinaloa Cartel now routinely manufactures the synthetic opioid, which is 50 to 100 times more powerful than opium, and then adds the fentanyl to its heroin to make a much stronger drug. It’s also more addicting and more deadly.

Do we still want to run away from this bear? Maybe, maybe not.

Republican presidential candidate Donald Trump recommends building a wall at the border, and letting Mexico pay for it.

“At one point,” Winslow writes, Guzmán “threatened to have Donald Trump whacked. Oddly enough, Trump didn’t respond with a dismissive nickname, maybe because, of all the Mexicans who would scratch a check for the wall, Guzmán would have jumped at the chance, as it would increase his profits.”