You're right, he sometimes conceals things and you wonder what his reasons might be. For example in the scene in TBB when he enters the flat and is nearly strangled while John is waiting outside, getting annoyed and saying funny things. He doesn't tell him why he's suddenly hoarse. Maybe it's because he regards it as a sort of defeat as he wasn't able to overpower the attacker.
Maybe he only bothers to correct people when it really matters to him. John didn't question his intelligence or power of deduction, he just called him lazy. In the cabbie scene, however, it mattered to him because he wanted to prove to another superior brain that he was right. And in the strangling scene he didn't want to appear weak or defeated.

SusiGo wrote:

You're right, he sometimes conceals things and you wonder what his reasons might be. For example in the scene in TBB when he enters the flat and is nearly strangled while John is waiting outside, getting annoyed and saying funny things. He doesn't tell him why he's suddenly hoarse. Maybe it's because he regards it as a sort of defeat as he wasn't able to overpower the attacker.
Maybe he only bothers to correct people when it really matters to him. John didn't question his intelligence or power of deduction, he just called him lazy. In the cabbie scene, however, it mattered to him because he wanted to prove to another superior brain that he was right. And in the strangling scene he didn't want to appear weak or defeated.

I was going to bring this up in the thread about the TBB. He didn't tell John about either case -- the fight in their own apartment, which he won, or the fight in Soo Lin's (is that her name?) apartment, which he did not. So, what is a reason that holds up for both? We know he is a showoff. He says so himself.

It shows he is human. Sometimes he doesn't care what people say when he knows they are wrong.That's self-confidence. He does mind though that Donovan calls him a freak in front of John who he wants to have around. That was being humiliated and challenged. He wants to know if was the right pill, both pills ended up on the floor so the only way to find out was to ask Hope the cabbie.

Likewise he is cynical about sentiment, yet he has several reminders of past cases and keeps Irene's phone. Very human to not be 100%  rational.

Davina wrote:

Both are, to a certain extent, used for their comedic value.

The fight with the Sikh ends up with humour as John rants at Sherlock for not having moved the whole time he has been out battling with the chip and pin machine, whereas, of course we know, Sherlock knows but Joh doesn't that he has been fighting. The final comic piece is Sherlock pushing the sword under the chair out of sight with his foot.

The fight in The Blind Banker is also funny as we watch as John is ranting (again) at Sherlock whilst the fight is taking place. Then Sherlock comes out all hoarse but unwilling to tell John why. Once again we know what has happened but John doesn't.

The sharing of these 'secret incidents' with the audience, ones that on Sherlock and we know about, binds us a little more to his character. We almost feel as if he has confided in us something that he is unwilling, for whatever reason, to confide in John his only friend.

I totally agree. I love the way John is totally oblivious to what really happened in both those scenes, it really lightens the mood.

And I would say it is not out of character for him to keep secrets just for the sake of it, he can be quite stubborn and childish if he feels like it.

Yes, it's absolutely in accordance with the canon that Sherlock keeps things from John. I think in the books he does so even more whereas in the films they conduct most of their investigations together. In the canon Sherlock has many hideaways throughout the city and often goes away for hours or even days without telling John what he's about to do.

Very interesting thread!
When reading your comments about him using this sentence as a means of protecting himself from appearing vulnerable, I instantly thought of the Mycroft/Sherlock scene in Scandal ("Caring is not an advantage").

I think it could also apply to this way of his. Maybe Sherlock was brought up not to care in any way, and caring about what people think can hurt if one starts to act in order to make a certain impression or to display a certain picture.
Sherlock build up the facade of one who is only interested in his own thoughts and opinions so he can't be hurt by all the terrible things that people think about him, as for exemple the whole freak-episode with Donovan shows.

Furthermore I think that in saying that he doesn't care he involuntarily shows his vulnerability and John instantly detects it.
If it weren't for his well hidden but still existing vulnerability and the therein lying humanity, their whole partnership wouldn't work the way it does.

I don't know if this is the right thread but I'll just put it here. There is quote from Sherlock which I find quite important and couldn't find anywhere mentioned. In the fireplace scene in Hounds he says:

"Look at me, I’m afraid, John. Afraid. I’ve always been able to keep myself distant, divorce myself from feelings, but look you see, body’s betraying me. Interesting, yes, emotions.�

So it is a conscious decision not to care, to separate himself from his own feelings and those of other people.

And, it was drug-induced.

Reading this I was reminded of the incident in SiB where Sherlock could not solve a case and he got angry when John put it in his blog. Obviously he didn't want the public to be aware of the fact that he failed. Therefore, perhaps he cares what people think of his intelligence, but not really anything else?

My two cents, if it really matters.

Interesting thread.

My comments will be limited to the BBC Sherlock version of the character. 

I have gotten the sense that Sherlock for the most part genuinely does not care what others think about him with some notable exceptions. The people he cares about are important to him and he does care what they think; John in particular. He also cares what someone he views as his intellectual equal thinks. 

Someone pointed out that he cared what the cabbie thought in SiP. That makes a sort of sense. This man, however common he may appear, had a mind that could grasp things almost on the same level as Sherlock. I say almost because I still did not get that he was really near Sherlock's level. The cabbie was excellent at reading people, but I think that was where his expertise ended. If he had Sherlock's ability then he would not be driving a cab. He only started killing people after he was diagnosed with an incurable aneurysm, so if he was as gifted as Sherlock then why did he not use that intelligence to find a better means of providing for himself and his family?

Moriarty - who genuinely is Sherlock’s intellectual equal is another possible exception. Sherlock made a comment that stands out. "Why is my brother so determined to bore me when somebody else is being so delightfully interesting?" Sherlock called his game "elegant" He definitely cared what this new adversary thought about him, but that all changed when Moriarty strapped a vest of explosives to John. From that point Sherlock only cared what Moriarty was thinking in relation to how he could trap him and ultimately defeat him.

Lestrade and Mrs. Hudson are also interesting cases. Sherlock very obviously respects Lestrade. To a point I believe that he cares what the man thinks, or else he wouldn’t use that little texting method to insert himself into a case that has caught his fancy. He has a need to impress Lestrade so based on that he does indeed care what the man thinks. 

Mrs. Hudson is unique. She is more than his land lady or “not his housekeeper” She is clearly a mother figure to him. He nearly killed the CIA agent who roughed her up. When Mycroft told her to shut up both he and John landed on him with both feet. Bottom line no one messes with Mrs. Hudson, so naturally he cares what she thinks. Every boy cares what mom thinks. It is plain old human nature. 

As for people like Donovan and Anderson, Kitty Riely, the press, his fans, and the common wealth; I got the distinct impression that he didn't give a flop what they thought.  The only time that caring about being called a freak by Donovan seemed apparent was when this occurred in front of John for the first time. Sherlock was certainly not happy with Donovan and that is most likely why he publicly humiliated her as well as Anderson in front of everyone. I know I laughed out loud with that comment about the state of Donovan's knees. He didn’t even give a dilly what the Queen thought; showing up at Buckingham palace in a sheet.

Mycroft is a tough one. There is obviously no love lost between them, but they are brothers, and Mycroft meeting him at the morgue after Irene Adler's apparent death gave us a small look at the dynamic behind the facade they both put up for everyone else. Does Sherlock care what Mycroft thinks about him? Maybe, maybe not. There is evidence to support both suppositions.

As far as the rest of the world - Every indication tells us that as long as the people who matter to him know who he really is, the rest of the world can take a flying leap being no skin off his nose. He even wonders why the press accusing him of misdeeds would bother John. He understands why it should bother him even though it doesn't, but he can't figure out why it should bother John.

This portrayal of Sherlock is intricate and complicated. That is probably why we all like it so much.