I want to discuss briefly Introverted Thinking (Ti) as a function for a moment.

Ti-types, more than any other, want to understand systems at a fundamental level, getting to the core principles. Unlike Te-types, they’re not satisfied with simply knowing isolated causal chains (i.e. if-then statements, such as “If I press this button then the third light goes on”).

Why?

Once you understand the system rather than simply its outer behaviour, it affords you independence by liberating you from only being able to work within certain contexts. In other words, if a condition outside of Te’s if-then-else chain is met, it’s out of luck while the Ti keeps motoring along.

Ti-types thus want to anchor observed causal chains to underlying principles. Their bias, then, is that all well-designed systems should be internally consistent, and it’s the seemingly arbitrary nature of Te that is the most frustrating to them.

But if we look at Heroes like Qui-Gon Jinn (The Phantom Menace) and perhaps Tron (Tron), as well as Father-figures like Harry Tuttle (Brazil), we get a better idea of the essence of Ti…

At heart, Ti is an approach to life whereby you’re guided by reasoned principles independent of the rules and laws of “the system”. The Ti mindset is that of an intellectual rebel who wants to come to conclusions on their own terms through reason without anyone else’s framework being imposed on them; furthermore, it’s a mindset that demands such conclusions to be present in order to guide actions.

In a sense, then, Ti is similar to Fi, except its conclusions are arrived at by intellectual reasoning instead of moral certitude through Feeling. Whereas Fi is concerned with the question “How do I feel about this?”, Ti instead involves asking “What do I think about this?” and indeed, it’s this question that preoccupies the consciousness of Ti-types (i.e. ISTPs and INTPs). This question is more than just an arbitrary judgement, however — it’s more like the Socratic method directed upon oneself, and perhaps that’s the perfect illustration of Ti at work.

To summarise, Introverted Thinking (Ti) is an approach to life that involves forming independently-derived principles based on an intellectual process of reasoning.