Ever since personality typing went mainstream, fans have fought over the personality types of famous literary characters – most notably, Sherlock Holmes. It usually winds up as a debate between INTP and INTJ, but neither one fits the canon Holmes. I recently addressed this on my tumblr, but will expound on it here.

The original Sherlock Holmes is a very warm, balanced, friendly, and well-behaved ISTP, and here’s why:

He uses introverted intuition and extroverted sensing, not extroverted intuition and introverted sensing.

The INTP’s third function is introverted sensing; working as a lower function, it remembers not facts but general impressions. Its second function (extroverted intuition) bounces off its third function, creating a multitude of likely scenarios, a dozen different possibilities based off one piece of evidence. The INTP’s mind internalizes an idea, processes it, then continues adding additional information; it seeks not to narrow down the process, but to expand on it, taking us from point A to point G in rapid succession. We can solve a problem, but damned if we know how we did it, or how to explain to you how we found the solution: we just know.


Contrast that with the canon Sherlock Holmes, who follows a very linear mental process, excluding excess information and narrowing it down to the cause of the crime and the eventual result – introverted intuition. He builds primarily off of observing minute details in his surroundings and using established facts to support his hypothesis, which is an obvious use of extroverted sensing. (“You see, but you do not observe. The distinction is clear!” – A Scandal in Bohemia) Holmes is using a combination of Se-Ni. He even describes introverted intuition multiple times in explaining to Watson how his mind works:

“In solving a problem of this sort, the grand thing is to be able to reason backward. That is a very useful accomplishment, and a very easy one, but people do not practice it much.” – A Study in Scarlet

Sherlock Holmes closed his eyes and placed his elbows upon the arms of his chair, with his fingertips together. “The ideal reasoner,” he remarked, “would, when he had once been shown a single fact in all its bearings, deduce from it not only all the chain of events which led up to it but also all the results which would follow from it.” – The Five Orange Pips

“… few people, however, who if you told them a result, would be able to evolve from their own inner consciousness what the steps were which led up to that result.” – A Study in Scarlet

That is introverted intuition: the ability to observe a situation and reason backwards to its cause and forward to the outcome.


Holmes prefers to wait and gather factual information before starting to form a hypothesis; he insists on basing his theories on tangible realities, which indicates a preference for Sensing as one of his top two functions. Sensors are more grounded and based in the moment where Intuitives focus on the future and generate possibilities. The former wants the facts first, the latter can deal with the facts later.

He uses introverted thinking rather than extroverted thinking. He prides himself on his analytical skills and ability to reason differently from his peers in law enforcement. Furthermore, he concludes that “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.” This statement is blatant introverted thinking; it looks inside the mind to draw a conclusion, with or without external evidence. Ti accepts that a lack of evidence can be evidence in and of itself, where Te is driven to base its logic in the outside world, through provable realities.

Holmes withholds information and explanations until after he has formed conclusions; he withdraws to his corner and pile of pillows with a pipe and thinks in absolute silence until he reasons out the crime in his head (again, introverted thinking). He then shares the solution rather than the thought process, until prompted (Ti solves, then shares; Te reasons aloud as it solves).


He shows extroverted feeling in his detached but warm approach to others, his talent for manipulation and disguise, and his hyper-active behavior. As a function that gathers energy from external sources and needs to express itself outwardly, Fe uses adaptation, mimicry and movement to blend in to an environment and put people at ease. Holmes is forever pacing and exclaiming with excitement (except when he lacks mental stimulation, then he’s lethargic). Holmes shuns his emotions because they block clear reasoning (the pitfall and benefit of a lesser function) but nevertheless still has it – enough to charm others when he needs to (The Master Blackmailer), and in needing affirmation from Watson. (He is, undeniably, a show-off.)

He hates only one criminal in the entire canon, not for any personal reason but because of his cruelty toward society at large for the purpose of self-gratification (The Master Blackmailer). On that case, Holmes allows the murderer of the blackmailer to escape because he feels she is undeserving of punishment and her crime is vindicated; he disobeys the law, because he decides to act within the spirit of it (protection) rather than the letter of it (wrong is wrong, and should be punished equally). He allows his Fe-driven compassion to dictate his moral behavior. He also references a willingness to kill to avenge his friends (“If you had killed Watson, you would not have got out of this room alive” – The Adventure of the Three Garridebs).

Lastly, Sherlock Holmes is vastly different from his older brother — he is energetic, driven, relentlessly focused while on a case (the third function of introverted intuition — the ability to cast aside external distractions and obsess on one thing), and somewhat frustrated by his brother’s laziness.

“He has no ambition and no energy. He will not even go out of his way to verify his own solutions, and would rather be considered wrong than take the trouble to prove himself right. Again and again I have taken a problem to him, and have received an explanation which has afterwards proved to be the correct one. And yet he was absolutely incapable of working out the practical points.” – The Adventure of the Greek Interpreter

Mycroft is able to solve crimes without needing to see external evidence or has no interest in proving his theories. He enjoys the mental exercise but once he’s solved the problem, he loses interest in seeing the case through to its completion. The INTP in the canon is Mycroft, not Holmes.