Let’s talk about introversion and extraversion for a bit, not how the way it’s typically explained, but from a cognitive function standpoint. When most people starting off in mbti think of these two things, they picture it as the way one takes in energy. Extroverts become energized by being around other people while introverts gain energy by being alone. While this explanation is slightly true, it is perhaps one of the most misleading things in regards describing what extraversion and introversion truly mean when it comes to Jung’s cognitive functions.

One book aptly explains these two things as the “directions of attention and energy flow.” Extraversion is aimed at the world. Introversion is aimed inward towards the self. Extraversion is objective. Introversion is subjective. Extraversion is collective. Introversion is individual. Extraversion is widespread and extensive. Introversion is deep and penetrating.

When it is said that extraversion is aimed at the world, it processes things the way they actually are and makes decisions based on what makes most sense to the world. It is in this sense that they are seen as objective rather than subjective. The best way to understand this is by viewing each of the extraverted cognitive functions individually and understanding the way they work as a whole:
Extraverted Feeling - Takes on the morals of the collective whole. Whatever makes moral sense to the world is how they decide their “emotional” actions. Thus they conform to what the world believes is just.
Extraverted Thinking - Bases logic upon what is proven valid and sound. If a notion has no solid proof to back up its claim, it will be brushed to the side. It has no room for baseless speculation. Thus it conforms to what is proven and accepted as logically true.
Extraverted Sensing - Takes in external material data based upon the five senses only. “This apple smells sweet.” “That sign is blue.” Sees things as the way they objectively are.
Extraverted Intuition - Extensively explores all ideas and possibilities, viewing each with equal merit. Each idea is equally plausible and thus should not be quickly condensed to one only.

When it is said that introversion is aimed towards the self, it processes things according to the person’s inward experience and makes decisions based on what makes the most sense to them personally. It is in this sense that they are seen as subjective rather than objective . The best way to understand this is by viewing each of the introverted cognitive functions individually and understanding the way they work as a whole:
Introverted Feeling - Bases morals and actions upon what the user personally feels to be right. Focuses more on what one is feeling than what the group is. Less likely to conform to the group dynamic.
Introverted Thinking - Bases logic upon what makes the most sense to them. Constantly revising and refining logic to fit new conclusions from internal analysis. Views logic bound by what has been proven to be too close-minded and strict.
Introverted Sensing - Compacts experiences into memory and processes external data by comparing it to past experience. “The last time I had an apple from this store, it was sweet.” “The blue sign seems a bit more faded from last year.” Rather than experience world in the moment, it always has an eye on their inward subjective memories.
Introverted Intuition - Synthesizes and condenses data into overlaying universal themes. Rather than view everything as equally likely, sticks to and intensively develops insight upon the one that makes the most sense to them.

Not surprisingly, it is commonly said that extraverted and introverted functions tend to repel each other. This is due to the opposite directions of attention and energy flow. Fe, in the view of Fi, it’s often seen as fake and morally weak. Fi is seen as selfish and self-righteous. Te is seen as too rigid and stubborn while Ti is too speculative and unrealistic. Se is too impulsive and frivolous while Si lives too much in the past and can’t enjoy life in the moment. Ne is too indecisive and unfocused while Ni is too decisive and stubborn.

Hopefully this helps to explain Jung’s theory of cognitive functions a bit more and what extraversion and introversion mean in that sense. These two things are a lot more than the way one gets energy.