Why are they having a normal conversation and occasionally switching to Parseltongue to confirm the more important bits? Why not conduct the entire conversation in Parseltongue? Seems like the best way to ensure full cooperation leading to superior outcomes for both parties. Harry has already sneaked one lie past Quirrell, and he has no idea how much of what Quirrell said is true outside of the parts he deliberately chose to speak in Parseltongue.
Parseltongue is a low-information-density language—it lacks a lot of technical terms, colloquial phrases, and the like. Communication is much faster in English.
Quirrell models himself as more intelligent than Harry, and has had far more time to plan, so he expects to win in any even contest. Being able to lie grants both parties great flexibility of options, which he expects to make better use of than Harry.
However, Quirrell seems to dislike lies—half truth, yes, misleading information, yes, but blatant lie is just not in his style. Whether this is an inherent feature of his character or sense of honour, or he wants to keep open the possibility to confirm his words later in Parseltongue if need be, that’s an open question.
The lips twitched again, and then went flat. “Then I shall skip it. Mr. Potter, you sometimes make a game of lying with truths, playing with words to conceal your meanings in plain sight. I, too, have been known to find that amusing. But if I so much as tell you what I hope we shall do this day, Mr. Potter, you will lie about it. You will lie straight out, without hesitation, without wordplay or hints, to anyone who asks about it, be they foe or closest friend. You will lie to Malfoy, to Granger, and to McGonagall. You will speak, always and without hesitation, in exactly the fashion you would speak if you knew nothing, with no concern for your honor. That also is how it must be.”
There was silence, then, for a time.
That was a price measured in a fraction of Harry’s soul.
Why are they having a normal conversation and occasionally switching to Parseltongue to confirm the more important bits? Why not conduct the entire conversation in Parseltongue? Seems like the best way to ensure full cooperation leading to superior outcomes for both parties. Harry has already sneaked one lie past Quirrell, and he has no idea how much of what Quirrell said is true outside of the parts he deliberately chose to speak in Parseltongue.
Parseltongue is a low-information-density language—it lacks a lot of technical terms, colloquial phrases, and the like. Communication is much faster in English.
Because EY wants the chapter to be not-annoying to read, might be one good reason.
Quirrell models himself as more intelligent than Harry, and has had far more time to plan, so he expects to win in any even contest. Being able to lie grants both parties great flexibility of options, which he expects to make better use of than Harry.
However, Quirrell seems to dislike lies—half truth, yes, misleading information, yes, but blatant lie is just not in his style. Whether this is an inherent feature of his character or sense of honour, or he wants to keep open the possibility to confirm his words later in Parseltongue if need be, that’s an open question.
Inherent feature. We’re told this in chapter 51:
If Voldemort doesn’t at least sometimes use English to tell the truth, he’ll never be able to lie to Harry again.