The thing is, at the edges of people's knowledge there are two issues. One is, people want to demonstrate what they know about the topic, even if they can't an

The thing is, at the edges of people's knowledge there are two issues. One is, people want to demonstrate what they know about the topic, even if they can't answer the specific question. If you ask me to explain elliptic curve cryptography, I can tell you that it's useful because it uses smaller keys then prime based RSA crypto, and that's something I'd want to mention to indicate that, despite the fact that I'd need to look at a book or writeup to actually implement elliptic curve cryptography and I'm not sure I can verbally explain the math behind it, I at least know something about it. The second is, at the limits of my domain knowledge, I may not know what I know and don't know. Limits are fuzzy, and I may feel like I have a pretty good understanding of a linux file system from a user perspective (permissions, inodes, etc) but I couldn't implement one off the top of my head and I'm probably missing some important components. As an interviewee, I may have incorrect or incomplete knowledge, but not know that. That doesn't mean I'm bullshitting intentionally, I'm just trying my best to answer the question I think you are asking. Also I have to think that other developer cultures may have different values around these ideas then my own. Maybe the cultural expectation is to show confidence in my ability; I know that confident individuals are more likely to get hired or even apply for jobs, and that often job requirements are a screen for confidence. Sure, I'd love if I knew every gap in my knowledge and every mistaken understanding I have, but I don't know how realistic it is to suggest a deliberate deception on the edge of a person's knowledge. And that's setting aside whether the interview process is a good predictor of workplace behavior... I think we all know people who are excellent devs that can't write on a white board for shit, or who sit down for a good think for an hour and then come up with a perfect solution but aren't going to be able to write and simultaneously talk you through a solution to a 15 minute data algorithm question.