How do I know/ How am I to know?



Is there any difference between these two questions? Is the second one grammatically right?

How do I know?


How am I to know?


Posted 2016-03-04T02:26:18.163

Reputation: 61

2They're both grammatical and correct, but mean (somewhat) different things. The question "How am I to know?" is the same as "How should I know?", that is: Why do you expect me to know? What reasons can you give me for your apparent expectation that I know that?. The first expression "How do I know?" can and has been used informally to express that same idea, but more formally is closer to an epistemological musing: How is that I came to know this thing?. So, in their formal senses, in the second question, you're implying don't know something, whereas in the first, that you do. – Dan Bron – 2016-03-04T02:31:07.247

@DanBron: I think that would do well as an answer with perhaps a bit more polishing. – Nathan Tuggy – 2016-03-04T02:34:07.513

@NathanTuggy The issue I have with posting an answer proper on ELL is that I am not versed enough in the mechanics of English (or linguistics in general) to justify an answer. And my instinct is that the implicit assertion "Trust me, I'm a native speaker" is insufficient and unfair to your community members who are learning English from the outside. Unless you regulars feel differently? – Dan Bron – 2016-03-04T02:36:15.543

@DanBron: Hmm, fair enough. I think you're pretty close to having enough justification, but I can see that there's a bit more that would be nice to have too. Perhaps I'll write up my take on why that is, if you don't mind giving me the inspiration. – Nathan Tuggy – 2016-03-04T02:42:10.700

@NathanTuggy I would love to see what you put together. I honestly learn more about English from you all on ELL than I do on ELU. – Dan Bron – 2016-03-04T02:43:40.763

@DanBron Can it apply the same way in this situation, when one ask you "how are you to know" instead of "how do you know"? – Gnoulv – 2016-03-04T02:49:03.397

@Gnoulv That's an analogous situation. If I ask you "How are you to know?", I am implying that you do not know, and it is unfair to expect you to know. If I ask you "How do you know?", then I responding to some knowledge you have just conveyed to me, and either asking for the source of your knowledge, or insinuating that I am skeptical. As in "Mary looks good naked" / "How do you know?" vs "Tom asked me whether Mary looks good naked" / "How are you to know?". That sort of thing. – Dan Bron – 2016-03-04T02:51:54.357

So can I apply the same question structure to other questions, like 'Are you to have a CD' instead of 'Do you have a CD' or 'Have you a CD'? – Gnoulv – 2016-03-04T02:56:41.197

@Gnoulv Nope. No, you can not. And I would warn you against trying to generalize, or over generalize, patterns in English, without corroborating those extensions. That's a significant source of error for a lot of second language leaners (it's called overregularization, and for a certain type of error hypercorrection). – Dan Bron – 2016-03-04T02:58:49.390

And should someone who is a English learner use the question 'Have you something'? I mean in your point of view. – Gnoulv – 2016-03-04T03:03:26.130

From an American perspective "Have you <something>?" rings of British English. If an American uses it himself, it comes across as an affectation (like signing off his emails with "Cheers!"). We Americans tend to say "Do you have <something>?". It's fine for a learner to use, yes, if your chosen dialect, the one you're most interested in emulating, is BrE, and particularly what's called "Received Pronunciation", which is the acrolect of English. No one could bregrudge you that! – Dan Bron – 2016-03-04T03:06:33.357

Another additional question, should I begin a sentence by 'and'/ 'but'? I am going to take IELTS test and my teacher always advises me definitely not to do so, as it will note examinators in a positive way, but to me it is a whole more ease to express my ideas if I could do so. – Gnoulv – 2016-03-04T03:13:40.800

Please forgive my plenty of question, but I would really grateful if you answered me just one more that question – Gnoulv – 2016-03-04T03:24:12.703

@Gnoulv In real life, and everyday speech and writing, starting sentences with "And" and "But" is perfectly fine and common and you should make no effort to avoid it. The highest echelons of English linguists and grammarians (to which I emphatically do not belong) would tell you the same. But, people like your teacher also exist, and the type of people who grade tests like the IELTS tend to fall into that category, so it would be wise to avoid doing so on your exam. – Dan Bron – 2016-03-04T03:24:56.533

@DanBron: I think I got something that's actually pretty good! Took me a bit of thought and research, I will say. – Nathan Tuggy – 2016-03-04T07:07:26.400



Dan Bron's opening comment is correct, but I'd like to explain a bit more about why that's the case.

Basically, it comes down to tense and modality, or conditionality. Using "to be" (or in this case, "am") with an infinitive like "to know" is one of the future tenses English uses*, and it's a tense that expresses intention and plan. So you could rephrase "How am I to know?" as "What plan would you expect me to use to know this?"

Since that's a fairly common sort of thing to say, but "How am I to …" is a fairly formal pattern, it's not surprising that "How do I …?" has been adapted to that use as well informally. Formally, though, "do" is not conditional at all here. It's just asking for a explanation that matches current reality. So you could rephrase it as "Right here, right now, how is it that I know this?"

Obviously, both sentences (and both verbs) are very flexible, so there's a lot of variations possible, and a lot of different subtle implications depending on context. But that's the basic breakdown.

*To the extent that English has future tense, at least, which is the subject of some scholarly debate. Close enough, though.

Nathan Tuggy

Posted 2016-03-04T02:26:18.163

Reputation: 9 403

Oh, interesting explanation. I'm going to have to mull it a bit. – Dan Bron – 2016-03-04T07:09:45.830

Understood. In addition, I have often read of such sentences, like those from arcticle titles: "Brazil to move...", "US to ban..." and alike. Are those a short form of that future tense? Does it mean "Brazil is going to move..."? – Gnoulv – 2016-03-04T12:46:25.047

@Gnoulv: Yep. "Headlinese" tends to leave out a lot of connecting pieces wherever possible, so it has some unusual appearances, but that's basically what that comes from. – Nathan Tuggy – 2016-03-04T17:56:59.143


Let's say you are solving a math problem You are stuck somewhere for hours and after hours of struggle you came to know the reason, that is you were unaware of a formula which happens to be out of scope for you. At that point you can say "how am i to know?" According to me, "How do I know" is more like a statement Let's say after hours of struggle you went for a drink and after returning you started again and you solved it. (rare scenario) Next day you find the solved problem in your bed. You checked and find a strange formula which solved it. At that point you may say "how do I know" since you don't remember solving it.

Shah Rukh K

Posted 2016-03-04T02:26:18.163

Reputation: 103