Parents' Guide

Ages 5 to 9
Logic and Critical Thinking

Parents' Guide

Ages 5 to 9
Logic and Critical Thinking

1. Logic and Critical Thinking

Differentiating logical thinking from critical thinking

Formal logic is an important part of critical thinking, but ultimately critical thinking involves habits and skills going far beyond the domain of logic. Children’s critical faculties, therefore, cannot be built from logical analysis, but rather develop out of everyday reasoning.

There are three main factors to keep in mind in differentiating logic from the everyday reasoning that underpins critical thinking.

1. Logic is not a natural human trait. If it were, we wouldn’t have to learn how to reason, and math wouldn’t be considered so difficult in school.

The natural reasoning displayed by children is often founded on sensory experiences and marred by the cognitive biases discussed in the introduction.

For example, if someone says: “If it rains, I’ll take my umbrella with me.”
And then a moment later adds: “It’s not raining.”
What may we conclude?

The vast majority of people—including both adults and children old enough to understand the question—will conclude that the person will not take an umbrella. In an everyday context, that is a reasonable conclusion to draw. But from a purely logical perspective,  it does not follow from the two statements. The fact that, if it does rain, the person will take an umbrella implies nothing, logically speaking, about what will be done if it is not raining

Close-Up: Logic and Brain Development

Complex reasoning predominantly takes place in the prefrontal cortex and areas of the brain devoted to language. Language development is, of course, closely linked to explicit learning, as well as to implicit stimulation.

But reasoning requires more than just language skills. The prefrontal cortex carries out what are known as executive functions. It controls concentration, planning, decision-making, and many other functions. These allow us to break down complex tasks into a series of simpler tasks. Reasoning requires a strategy that breaks things down. The prefrontal lobe is a cerebral zone that only matures neurologically after the age of 20. 

Logic is neither natural nor easy. Its development requires a comfortable handling of language and the capacity for problem-solving in the prefrontal cortex. Where are we now? Where do we want to go? How can we get there?

Case in Point

We show children from this age group a drawing of a rectangular flask tipped at an angle, and we ask them: “If I fill this flask roughly halfway, could you draw the water line on the flask?” 

What would be the result? Most children will draw a line perpendicular to the flask’s longitudinal axis. Yet, since this axis does not run vertically but, rather, is at an angle, the line the child draws is not horizontal relative to the ground, as it should be. 

Children err here because their minds are referentially anchored to the flask, just as astronomers for many millennia were fixated on the idea of the earth, and later the sun, as a reference point—before realizing that the universe does not have an absolute reference point.

Even if we explain the error to children—and they say they understand—many will, shortly afterwards, make the same mistake again. Their cognitive system is not mature enough to incorporate the logic behind reference and relativity. The example shows how logical thinking is not natural, but requires a learned ability to step back and remove oneself from immediate engagement with a particular situation. 

Logic, the cognitive capacity for formal and reliable deduction, is not natural to humans and can only be acquired through learning—and only at an age when the cognitive system and brain development allow for such learning (between ages 12 and 15).

2. Logic is not natural but it can be taught with varying degrees of success, according to personality, cognitive profile, and so on. Multiple developmental psychology studies since Piaget have shown that our cognitive system can only become proficient in logical analysis later on, and with the correct training.

3. If we train children from ages five to nine to make more or less complex logical deductions, no deep knowledge is acquired: at this age, the cognitive system does not yet have the capacity to discern logical invariables (i.e., the ability to reproduce a line of reasoning in a variable context). This is why mathematical principles are only explained to children when they are 13 to 14 years old.


Case Study 1