Introverted Thinking is an internal-facing, subjective, decision-focused cognitive function. If that sounds like a vomit of abstract words, it’s because it is: Ti is hard to define because it’s a deeply personal logical framework. Contrast Ti against Te (extraverted Thinking). Te is characterized by efficiency, affecting external change, and order. But while Ti is also rational and object-focused, it’s less concerned with implementable efficiency and more concerned with truth: why is the world the way it is? How do I live and feel that truth?
What is high Ti good at?
High-Ti users are well known for being independent thinkers. They rarely take declarations of the world as-is; instead, they turn facts and theories in their head, examining them from every angle and triangulating them against their known logic. Unless coming from someone that truly matters to them, Ti is generally unaffected by social pressure and coercive methods, letting high-Ti users maintain an objective, impersonal perspective in even high-stakes situations.
Ti is a “sharp” function. While INTPs and ISTPs are often stereotyped as lethargic (and from anecdotal experience, they really do seem to enjoy sleeping), and ENTPs and ESTPs stereotyped as trolly or thrill-seeking, a Ti-user when “on” is crisp, supremely observant, and capable of detecting and exploiting logical flaws. Because they spend so much time working out the foundational framework of their rationality, they can spot irrational arguments in a second–and boy, is there a lot of irrationality in the world. Ti users are happy to indulge in stupidity for fun or for things they don’t care about, but in meaningful matters very little escapes their sharp judgement.
Freed from the constraints of extraverted Judgement efficiency, Ti can create groundbreaking shifts in our understanding of truth. Unlike Te, which always has an eye towards pragmatism, the insights of Ti can lends itself towards dogged pursuit of an idea even if nobody else–church, state, society, or the free market–has rewarded it yet. Many pioneering scientists and champion athletes are Ti-dom or Ti-aux, as both fields require significant amounts of investment before reaping any benefit. “Truth” doesn’t always have to be serious, either; the character Mr. Bean (INTP) often inadvertently shakes a situation via an out-of-the-box solution that cuts through social and structural niceties.
Ti/Se vs. Ti/Ne
Typically types that share a dominant function share significant similarities (e.g. ENFJ and ESFJ), but Ti/Se and Ti/Ne are one of the most dissimilar sister types in the MBTI family. This is because Ti is a deeply personal logical framework; when applied in different directions via Se and Ne, it results in completely different focuses.
Lenore Thomson says it best for Ti/Se: “When Introverted Thinking is combined with Extraverted Sensation… it feels a lot like instinct.” (Personality Type, pg. 288) Se feeds direct sensory experience to Ti, which responds so instantly in the moment that it looks less like “thinking” as it does just “doing.” While ISTPs and ESTPs are stimulated by physical thrill–motorcycling, woodworking, rocking a guitar onstage–they’re just as invigorated by the thrill of a business negotiation, the stressful pressure of performing a heart surgery, the articulation of what makes a complex mechanical watch work (or not work). Ti/Se needs to feel “fire on the skin,” and ESTPs and ISTPs welcome the opportunity to learn and sharpen their logic against the reality of the world.
Ti/Ne is more traditionally cerebral, directing their energy towards ideas, possibilities, and theories. There’s a reason why championship echelons of chess and poker are packed with ENTPs and INTPs, whose combination of sharp, complex logic (Ti) and holistic imagination of possibilities (Ne) gives them an edge. XNTPs are often interested and knowledgeable in a wide range of areas, but really get a kick out of subjects that they can “nerd out” and get deep into. That doesn’t mean they’re holed up in basements in front of chalkboards–befriend any ENTP and you’ll see that’s not the case–but their logic shines most in the systematic, creative abstract.
Ti is so coloured by its corresponding Ne/Se functions that ISTPs and ESTPs look drastically different from INTPs and ENTPs. The shared Ti usually becomes most evident when: (1) they get the chance to explain their thought process in depth, and (2) when ESTPs and ENTPs gang up to troll other people.
Extraverted vs. Introverted TPs
Our introverted/extraverted counterparts are one of our closest cousins. INTPs will understand and recognize similar thought processes in ENTPs, and ISTPs will see the same with ESTPs. So what might be some I/E differences?
Ti is a subjective, internal decision function. ISTPs and INTPs–who have Ti as a dominant function–will trust their own judgement above all. They are slower to act and more thorough with their understanding, wanting to think through and feel all the edge cases, all the intricacies and mechanics. Their auxiliary functions (Se and Ne respectively) feed much-required data and ideas, but is not the starting point. IXTPs are comparatively more patient, more willing to spend copious amounts of time alone to refine their projects, and as a result more eccentric than their EXTP counterparts.
ESTPs and ENTPs take the objective world first and apply their logic to it second. With an extraverted perceiving function (Se and Ne, respectively), the world is exciting, thrilling, brimming with possibilities, and must be responded to. They’re willing to pursue an exciting opportunity even if it doesn’t yet fit with their subjective logical framework. EXTPs will react faster, be more outspoken, and are generally more socially engaged than IXTPs.
Because extraverted Perceiving functions are so excited by the world’s possibilities, ESTPs and ENTPs will come across more excited, alert, and witty compared to the more lethargic, analytical, thoughtful ISTPs and INTPs. That being said, XSTPs and XNTPs are going to share more similarities than differences when compared to other MBTI types.
The role of Fe
Fe is the natural opposite of Ti, being the external, objective personal. ISTPs and INTPs (with inferior Fe) and ESTPs and ENTPs (with tertiary Fe) need to work lifelong to develop a health relationship with their Fe function.
Fe is the achilles heel of INTPs and ISTPs. They may deeply care about their friends, family, and coworkers, but find that the right words and actions in a relational setting escapes them. They may intuit that there are invisible social rules but anxiously realize they don’t know them. Teenage IXTPs often explode in the heat of the moment with emotion, only to wonder what happened after they cool down. While brilliant in individual discovery, IXTPs can sometimes be frustrating team members who block decisions until they personally understand them, sacrificing collaborative Fe on the altar of personal Ti.
Fe works a bit differently for ESTPs and ENTPs; being a tertiary function, their Fe is strong enough to understand the contours of social dynamics and play around with them, but not strong enough to be held back by it (see ESTP vs. ENTP in leadership). This means they often push the boundaries of social acceptability, conveying blunt feedback with just enough humour to be accepted; however, every EXTPs has had an experience in which they pushed too far with someone they cared too much about. When engaging well with their Fe, EXTPs can be quite charismatic.
Tertiary/inferior Fe lends an awkward sincerity to the TPs. As they get older, they learn enough social rules so that social situations no longer paralyze them. They learn when their actions might be taken for coldness and adjust appropriately, and they learn how to care for the people they love. While TPs may never be stereotypically warm, healthy, mature TPs acknowledge how much their friendships and relationships mean to them and work to maintain them. The TPs who have put in the work to mature their Fe will find themselves with a group of friends who love them with no boundaries.