Here are some facts to chew on: About one in three highly successful entrepreneurs — including the founders of JetBlue, Charles Schwab and Kinkos — are dyslexic.

Two-thirds of British prime ministers at the peak of the empire, and almost a third of all US presidents, lost a parent when they were a child. These are among the arguments for unexpected sources of strength that Malcolm Gladwell explores in his new book, “David and Goliath: Underdogs, Misfits, and the Art of Battling Giants.” Gladwell, a writer for The New Yorker whose previous books include “Blink,” ‘’The Tipping Point” and “Outliers,” has made it his specialty to challenge assumptions and conventional wisdom.

In “David and Goliath,” Gladwell argues that sometimes what we think of as disadvantages can work in our favor. He puts this theory to test with stories of an underdog girls’ basketball team that makes it to the nationals; various school class-size experiments; and the Big Fish-Little Pond Effect.