What is the difference between 防ぐ and 予防する ?

To me both of them seem to mean "to prevent".  
A Japanese person once explained to me how they are different but
unfortunately I don't remember.

Similar question: [What is the difference between 防止 and
予防?](https://japanese.stackexchange.com/questions/6436/what-is-the-difference-
between-%E9%98%B2%E6%AD%A2-and-%E4%BA%88%E9%98%B2)
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2013-07-10T05:30:04.887
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word-choice nuances
Difference between 防ぐ and 予防する
Sorry to be perhaps a little obvious, but isn't the difference that one is a
verb and the other is a noun made into a verb, where the difference in
grammatical construct carries its own nuance?

In English we can do a similar thing with the root word "prevent". We can
either use it as a noun, "a prevention (against...)", or we can use it as a
verb, "to prevent (something...)".

`する` isn't exactly "enact", but `予防する` would translate to me as "enact a
prevention" against something happening, whereas `防ぐ` is simply "to prevent".
It's like the difference between "going for a run" and "going running". Or
`散歩する` and `歩く`, to use a Japanese example. Same meaning, different nuance.
Using the verb simply names an action with open ended parameters, using the
noun delineates that activity as a more specific task with known and set
parameters.

Bottom line is that I think they do mean the same thing, the difference only
lies in the nuance that exists _any_ time you choose between a verb or noun-
made-verb.
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2013-07-10T06:16:07.537
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予防する ＝ 予め防ぐ. 予 of 予防する means 予め（あらかじめ, in advance）. So 予防する is to prevent in
advance. Yes, the meaning of 防ぐ(prevent) itself includes the concept 'in
advance', but 予防する emphasizes the meaning.

我々は火の手が広まらないように防いだ.(We prevented the fire from spreading. ) In this case, we
don't say 予防した, because the fire actually happened already.
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2013-07-16T06:08:11.980
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There's a little more nuance to it than one being 'in advance,' I think. 予防 is
used in limited situations to refer to prevention of certain medical or
natural disasters, usually referring to preventive measures taken to protect
against fire, or something like vaccinations to prevent illness. If you check
this [dictionary entry for
予防](http://www.weblio.jp/content/%E4%BA%88%E9%98%B2) you get a single,
specific answer:

> 病気や災害などが生じないように注意し、前もって防ぐこと。  
>  「火災を―する」「―措置」

To translate, it refers to advance prevention, as we see in 予, but it
specifically refers to things like illness and natural disasters.

The [definitions for 防ぐ](http://www.weblio.jp/content/%E9%98%B2%E3%81%90) on
the other hand are rather varied and have much more of a physical nuance of
preventing something on the outside from getting inside something, much more
in the sense of defense rather than in prevention. Indeed, prevention can be
seen as an advance defense, but 防ぐ is more about the act of keeping something
out rather than the action as a meditated action in regard to an anticipated
event.

To steal a few examples from that dictionary entry:
「敵の猛攻を―・ぐ」「外敵の侵入を―・ぐ」「冷たい北風を―・ぐ」「西日を―・ぐ」

Apparently one of the definitions allows for a similar meaning to 予防, as in
here:

> (3)悪いことが起ころうとするのを、あらかじめ手段を講じてくいとめる。防止する。  
>  「病害虫の発生を―・ぐ」「事故を未然に―・ぐ」

But the dictionary itself defines it as 防止 rather than 予防, which is basically
the difference between "halt/stop from happening" and "take early defensive
action."
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2013-07-16T06:28:09.213
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防ぐ is used to express more of an instant/direct action of blocking/preventing
something turning towards wrong condition.

However 予防する is used to generically express blocking/preventing something to
turn towards a wrong condition.

So, データの流出を **防ぐ** sounds more natural than データの流出を **予防する**. The former often
requires a direct action to do so. It is not like an immune system to block
viruses which innately equipped to human beings.

It can be synonymous how you use, but the basically it sounds like this to me.
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2023-05-18T04:48:29.553
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