In my native language we have the expression "only iron can cut iron" which means: a force is best confronted with a force of the same nature, or: it takes someone at the same level as someone else to defeat them.

For example:

It wasn't until yesterday that this arrogant man realized he wasn't the best chess player in the world when that guy from the other neighborhood beat him. Only iron can cut iron.

Other examples:

  • vaccines that use a weakened form of the virus that causes a disease.
  • Using controlled fires to stop a wildfire.

Is there an idiom with the same meaning in English?

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    Another example, but not a direct meaning of the question's title, is set a thief to catch a thief. Commented Jun 13, 2021 at 20:15
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    AFAIK, there really isn't an exact match. "Fighting fire with fire" comes close, but it doesn't include the "only" part - there are lots of ways to fight fire. And of course the expression is factually just plain wrong: there are lots of ways to cut iron that don't involve iron.
    – jamesqf
    Commented Jun 14, 2021 at 15:56
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    somewhat similar (and a bit gruesome) is "don't take a knife to a gunfight"
    – Fattie
    Commented Jun 14, 2021 at 17:05
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    @Fattie: But (at least as far as I've seen it) the English expression is not "it takes fire.." (implying that fire is the only or best way to fight fire), it's "using fire to fight fire", implying that 1) it's not the only possible way; and 2) there's something of a surprise/irony in using fire that way.
    – jamesqf
    Commented Jun 14, 2021 at 22:12
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    The man in the example got a taste of his own medicine. Commented Jun 14, 2021 at 22:52

7 Answers 7


In English, we have diamond cut diamond, although I think fight fire with fire is more appropriate in the situation described in the OP.

Fight fire with fire: to use the same methods as someone else in order to defeat them.

[Cambridge English Dictionary]

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    Note that "fight fire with fire" is very often used in a negative context, meaning to do a distasteful thing because it is the only way to achieve victory over an opponent who is already doing the distasteful thing.
    – randomhead
    Commented Jun 13, 2021 at 20:02
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    I don't think this works in the given example, although it sounds like it might work in other contexts which "only iron can cut iron" is used in. It doesn't imply anything about skill level, only methods, IMO.
    – Kat
    Commented Jun 14, 2021 at 5:25
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    @Kat The OP used the example of using a controlled fire to stop a wildfire, which is exactly where this idiom comes from.
    – Barmar
    Commented Jun 14, 2021 at 14:25
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    See, the diamond one is actually accurate. There's really any number of things that can cut iron, but diamonds actually can't be scratched without using another diamond (or perhaps some advanced laser/plasma cutting devices or something.) But why let physics stand in the way of a perfectly good metaphor? Commented Jun 14, 2021 at 15:44
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    We have 'diamond cut diamond'? Well, that's news to me.
    – Strawberry
    Commented Jun 15, 2021 at 15:18


a force is best confronted with a force of the same nature


  • Using controlled fires to stop a wildfire.

Are very directly equivalent to fight fire with fire, as per the existing answer.


it takes someone at the same level as someone else to defeat them

isn't really the same idiom in English.

Something like set a thief to catch a thief or the related poacher turned gamekeeper both mean using someone's expertise to defeat someone else with the same area of expertise, but note that their aims are not the same: they're not both competing to steal something, instead one is using their knowledge of stealing to prevent the theft.

I can't think of a set phrase that covers all your cases, but the closest for your chess example would be beaten at his own game. This is explicitly losing a competition using your own methods, although the expertise of the victor isn't really explicit.


This is actually a biblical reference:

Iron sharpens iron, So one man sharpens another. Proverbs 27:17 (NASB)

So, at least in English-speaking Judeo-Christian circles, the idiom stands as-is and is relatively well recognized as a biblical proverb. It has the expanded meaning that a person of strong faith can help a person of weaker faith grow by relating their experiences and understanding of biblical truths.

In many circles, it is referenced in more confrontational terms: A faithful Christian may invoke this verse to chastise a fellow Christian who is not faithful to his wife, in the sense that it is his duty to remind the weaker brother that his actions represent a lifestyle of sin - regarded in many Christian circles as an indicator that the person never really accepted the teachings of Jesus Christ, or accepted them and later rejected them.

It is not difficult to see how this idiom evolved over time to more mundane conflicts, such as the better chess player that chastises the arrogant amateur by handily defeating them in a fair match.


There is also the phrase "Steel sharpens steel".

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    Welcome to English Language Learners! While this may be correct, we like our answers to be backed up by references. You can edit your answer to include one (e.g. an online dictionary). See the Help Center article How to Answer.
    – Glorfindel
    Commented Jun 14, 2021 at 14:03
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    While the words of the idiom are similar, I don't think it's relevant because it doesn't mean anything like what the OP is describing. "Steel sharpens steel" is a biblical proverb that describes how a good relationship strengthens both participants, nothing to do with needing a similar force to defeat somebody. Commented Jun 14, 2021 at 14:40

there is a saying common in comic books that says only a god can kill a god

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    From the looks of it, it seems that this could be a very fitting idiom. If you would provide at least one source or reference for that claim (a link to a dictionary, or an article discussing this idiom, or directly to a panel in a comic book using it) showing that it is actually used in that meaning, It'd be worth an up-vote for me. Just mention me in a comment here, then, and I'll vote for your answer! Commented Jun 16, 2021 at 8:57

I can't really think of an idiom that means exactly what you are asking for.

The closest thing I can come up with is similar in context:

To be the man, you have to beat the man

which was a catch-phrase popularized by wrestling legend Ric Flair.

However, it means that if you want to be considered the best, you have to beat whoever is currently the best.


In the sense that "a force is best confronted with a force of the same nature", we might say in English

we will hoist him with his own petard

meaning we plan on employing the methods he himself uses in order to "beat him at his own game", an expression which itself could be considered a response to the OP's request.

The expression is much more commonly given as "he was hoisted by his own petard", meaning someone undone by their own plans or actions, without the interference of others, but it can be, and often is, used in the sense of the OP as deliberately employing the particular methods or strategies of another person to defeat them.

For example,

Michigan AFL-CIO President Mark Gaffney said his union will remind voters often between now and the November election that McCain supports national right-to-work measures; voted for free-trade agreements that have sent jobs abroad; and promotes a health care plan that would tax benefits. "Our best approach is going to be his record, which is quite anti-worker, anti-middle class, anti-union," Gaffney said. "We will hoist him on his own petard," Gaffney said.

Another example, another, and another.

It is a particularly English expression because it is derived from Shakespeare's Hamlet and thus has found its way into far fewer languages than the Bible.

As an unrelated note, other commenters and answers have mentioned "set a thief to catch a thief". I agree with this, but at least in American English I have almost always heard this as "it takes a thief to catch a thief" which I think is less about 'this is what we are going to do' and more about 'this is what one would need to do; this is how the world works', and so is closer to what the OP is requesting.

  • Given the contours of this question, I'd say that "beat him at his own game" is a marginally better answer than "hoist him with his own petard". Commented Jun 15, 2021 at 22:26
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    Pretty sure that "hoisted by his own petard" is wrong. It means that someone is undone by their own schemes and plans; it's a reference to primitive bombs (petards) that were composed of a barrel full of gunpowder - and the "hoisting" is when one goes off while you're handling it and kills you.
    – nick012000
    Commented Jun 16, 2021 at 0:36
  • @nick012000 When done to oneself, it does not match the OP's use, and this is the more common expression. However, it can be used in the sense of employing someone's own tactics against them - I have edited in a quote.
    – Kirt
    Commented Jun 16, 2021 at 4:09
  • @Kirt The meaning of the phrase is still to destroy someone as a result of their own actions, though - if you're hoisting someone else with their own petard, then you're deliberately causing this to happen - a related idiom might be "give them enough rope to hang themselves", depending on how you cause this to happen (giving them the ability to mess things up on their own vs deliberately sabotaging their project).
    – nick012000
    Commented Jun 16, 2021 at 4:22
  • The expression "hoist by his own petard" is about self-inflicted damage, not something you do to someone. And it is 'hoist' not 'hoisted', as the second link in the answer correctly gives, which also says it is applied to "someone who has been scuppered by their own schemes". You can always find examples of mis-use. Commented Jun 16, 2021 at 17:51

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