Personality type reflects the extent we rely on words and the categories that words create. The Myers-Briggs system uses 4 categories. Why? The last letter represents how we make ourselves known to others. Those who rely primarily on words and the categories words create to make themselves known to others are called Judging, and extrovert their Decision Making function. Those who do not trust words and rely on a more holistic process to make themselves known to others are called Perceiving, and extrovert their Information Gathering function.
From there it seems reasonable to discuss the Decision Making and Information Gathering functions. Those who rely primarily on words and the categories words create to guide their decision-making are called Thinking. Those who rely on a more holistic process to make decisions are called Feeling.
Those who rely primarily on words and the categories words create to gather information are called Sensing. Those who rely on a more holistic process to gather information are called Intuiting.
Finally, what’s left is how we get our energy. Those who prefer words and the categories words create for their energy we call Extroverts. Those who draw their energy through a time of reflection and temporary retreat from words we call Introverts.
Thus we have four personality sphers, each with the possible letters ESTJ or INFP. ESTJs rely on words and the categories words create in each sphere, while INFPs rely on a more holistic process drawing from both words and the biological instinct.
For instance, I am INTP. I rely on a holistic process to get my energy (I), gather information (N), and make myself known to others (P). However, I rely primarily on words alone to make decisions. This is true, as I am very distrustful and skeptical of things in general, but demand a strict logical consistency of my actions.