There's a book that I was reading where a person has just found out about ionizing radiation. He says the following sentence:

Thanks. Now I know how my friends died.

The answer to that question is "radiation sickness". But that got me thinking: the author is right to use "how" here, but he could also have used "why" couldn't he?

Thanks. Now I know why my friends died.

There's a minute difference between "how" the friends died (radiation causing cell death; out of all the ways, that's the way it happened) and "why" they died (due to being exposed to radiation; if they hadn't, they'd have been alive) and "how" actually seems more correct but I just keep feeling "why" could have been used here as well.

Am I right? Is it interchangeable, or "how" should always be used?

  • As PPH's answer suggests, why they died is more often used to mean 'what were the circumstances that put them in a life-threatening situation' rather than 'what was the (medical) cause of death'. Apr 15, 2022 at 15:32
  • They'd normally mean exactly the same thing, but note that I don't know how you could think that! and I don't know why you would think that! always use could / would that way round. No-one would normally say I don't know how you would think that! or I don't know why you could think that! Noting that "obligatory" change in the auxiliary verb may help you understand how/why both "wh-words" can be used with much the same meaning in that particular context. Apr 15, 2022 at 15:39
  • @KateBunting Yes, that's what I mean to imply by giving the examples.
    – cst1992
    Apr 15, 2022 at 21:08

2 Answers 2


"How" and "why" mean different things. Your example is no exception, it's just that you've found a context where they elicit the same answer, but only because the answer has been abbreviated.

  • How did they die? They got radiation sickness.
  • Why did they die? The radiation sickness killed them.

'How' asks for the circumstances or events leading up to the death. 'Why' asks for the reason they died. Those could be the same, but not always. For example, if the circumstance of a person's death was a car accident, the reason they died might be head trauma. Or, if a person took their own life, asking 'how' might mean the method they used, but asking 'why' might get the response that they had depression.

  • I get your point. In that case, instead of answering the "why" with "because, radiation sickness", it'd make more sense to say: "because they weren't protected from the radiation".
    – cst1992
    Apr 15, 2022 at 21:10
  • And yes, your answer reinforces the point that "how" is better in this context - the person simply doesn't know about radiation before and now does, so he's clear on how it happened, medically.
    – cst1992
    Apr 15, 2022 at 21:11

There is a hell of a lot of difference between "how" and "why" as I'm sure you would agree. It is true however that languages are the inadequate means of communication of an inadequate species. It's true as well that things tend to overlap in the real world. So where will this lead us?

I know how you bought your brand-new Ferrari.
(Did you steal money from your dying grandmother?)
I know why you bought your brand-new Ferrari.

(To show off? Of course not, god forbid!)

I know how my friend died.
(Garrotted by some assassin?)
I know why my friend died.
(Was he or she brave/foolish enough to try to take on a corrupt system? A thorn in the side of the powers that be?)

  • People, please don't do emotional downvoting...
    – cst1992
    Apr 15, 2022 at 21:12

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