Some children seem blessed, almost from birth, with a capacity for critical thinking. They won't let a fallacious argument pass unnoticed or unscathed. And some are fortunate enough to be exposed at an early age to fine examples of good reasoning. In their listening and their reading they learn, by intellectual osmosis as it were, to think logically. Yet even these fortunate ones, like the rest of us, can benefit by having their logical intuitions and reasoning skills sharpened by precept and practice.