Here are some of the ways to distinguish between a type with extroverted logic (Te) and introverted logic (Ti) when it is the lead function.
First, it is important to keep in mind that no function works by itself. Te always works with Fi, and Ti always work with Fe. All 8 functions work together in the human psyche. But for simplicity we will focus just on the logical aspects.
Rules are the domain of logic. Both Te and Ti. The difference is how are these rules being accepted and applied.
As an introverted function, Ti looks within itself to determine rules. “What do I think about this? Does this make sense to me?” Ti strongly relies on internal information and internal frameworks to come to conclusions. A Ti type needs to think about external laws and rules and determine if they fit into their way of seeing things, their internal logical framework. Each piece of information is like a puzzle piece that they are trying to fit into their existing mental puzzle. If the piece of information doesn’t fit correctly, they reject it. If the “puzzle piece” does fit, then they accept the rules and will strictly adhere to them. For Ti types, their own judgment has the final say. The Ti type chooses the method that they think is best, and then desire everyone else to adhere to this method as well. It is not objective and may be seen as only an opinion to Te valuing types.
As an extroverted function, Te looks outside of itself to determine rules. “What do outside sources think about this? Does this make sense to the majority of experts? What is the established law?” Te strongly relies on external information and external frameworks to come to conclusions. A Te type does not need to decide whether or not the rule makes sense to them, because they trust reliable external sources more than their internal framework (Ti-ignoring). External rules or information from credible books or manuals are strictly adhered to by Te types because they trust external sources. If an external source says something and it comes from a reliable or authoritative expert (Fi involved here as well), the Te type will accept it. For Te types, the external authority has the final say. It is objective information without analyzing the relationships between things, which may be seen as unsatisfying to Ti valuing types.
Te: “This is what the instructions in the manual say, so this must be the best method. I will follow what it says.”
Ti: “This is what the instructions in the manual say, but I know a better way. I will follow my own short cut.”
Another good example of the above can be seen in Harry Potter and the Half-Blood Prince. Hermione (an LSE) is irritated that Harry is ignoring the instructions that are written in the textbook and is using a different method. When Harry tells her to crush instead of cutting, she replies: “No; the directions specifically say to cut.” Although Harry is getting better results than Hermione by ignoring the rules and following a different method, Hermione refuses to deviate from the instructions in the manual. As a lead Te type, she believes following the rules and laws in the manual (an external source) is what will lead to the best result. Of course, this would manifest differently for an LIE due to strong intuition (intuition enables greater experimentation), however, the essence of needing external sources of information remains the same.
Te: “There is consensus of expert opinion, and evidence to back this up. Therefore, I am inclined to believe it is true.”
Ti: “There is no consensus of opinion and no evidence to back this up, but it makes sense to me. Therefore, I am inclined to believe it is true.”
Te: “That isn’t what I thought. But scientific journals say it is true, and there is evidence, so I am probably wrong. I will update my understanding of the world.” (Te types ignore personal logic in favor of external sources)
Ti: “That isn’t what I thought. Scientific journals say it is true, and there is evidence, but it doesn’t fit into my understanding of the world, so the scientific journals are probably wrong.” (Ti types ignore external sources in favor of personal logic)
Both Te and Ti types may spend a lot of time reading and researching various topics, but the reasons are different. Because Te relies on external information, Te types are reading and researching to build up their knowledge base, which can lead them to be very knowledgeable about many things. Te types gather a lot of facts. If they are studying something in history, they will want to visit the historical site in person because it is important for them to see what they are learning in the external world. A Ti type may read and research a lot because they want to gain clarity and improve the depth of their understanding. They are trying to strengthen the links within their internal framework, gaining a greater overall picture of the puzzle.
Another thing to consider is the goals of Te compared to Ti. As an extroverted function, Te uses logic to make an impact on the environment. It does this by using logic to determine what is the most practical, efficient way to accomplish external goals. Te is concerned not only with external rules and laws, but also with processes, how things are being applied. Ti, as an introverted function, uses logic to find clarity and understanding. Since Ti relies on internal information (it’s own “internal puzzle”), consistency is important. They need consistency in thinking because they don’t use external rules to govern their actions.
Te seeks to understand how an object can be used in the environment.
Ti seeks to understand relationships between objects.
For example, let’s say a Te type and a Ti type are both presented with a hammer:
Te: “This is a hammer. It is useful in many ways. It can be used for construction. It can be used to hit nails into a wall. It can be used as a weapon. Hammers can be made from many different materials. Humans have been using hammers for thousands of years.”
Ti: “This is a hammer. Hammers belong to the category of tools. Hammers are a type of construction tool. Hammers are similar to screwdrivers because they are both tools. When I see a tool shaped this way, I know it is a hammer and can always classify it as a hammer.”
Te wants to know what it can do with the hammer in the external environment. What is it’s practical use? How is it useful? It is trying to apply things. Ti, however, is analyzing the hammer. It is examining the relationship of the hammer to other objects. What kind of tool is a hammer? How is a hammer related to other tools? It is trying to make sense of things.
In summary, Te is about using and applying logic to do something in the external world. Ti is about using logic to analyze and understand, providing greater internal clarity. Both are the realm of laws and rules, but the approach and motivations behind them are very different.
