The words 存じ上げません(Zonjiagemasen) and わかりかねます (Wakarikanemasu) both mean a polite form of “I don’t know” and although their original meanings are slightly different, they tend to be used interchangeably. Both of these words are often used in business situations as they are honorific language.
Difference between 存じ上げません(Zonjiagemasen) and わかりかねます (Wakarikanemasu)
Both of these words are polite ways of “I don’t know” or “I don’t understand” but there are slight differences in their usage. Both words are a polite expression that can be used for people in a superior position but the main difference is that 存じ上げません(Zonjiagemasen) is a softer expression than わかりかねます (Wakarikanemasu). Both words are polite expressions so using either would not be considered rude. However, 存じ上げません(Zonjiagemasen) is a negative expression, it may not be suitable for some situations so make sure you use it properly. Both 存じ上げません(Zonjiagemasen) is a softer expression than わかりかねます (Wakarikanemasu) can be translated into English as "I don't know," "I have no idea," or "I can not answer.
Definition of 存じ上げません(Zonjiagemasen)
存じ上げません(Zonjiagemasen) is 謙譲語(Kenjo-go) of not knowing. 謙譲語(Kenjo-go) is to show respect to others by expressing one’s action lower than the other. Since 存じ上げません(Zonjiagemasen) is a type of honorific language, it can be used in business situations when talking to people who are superior such as your boss or clients. For the antonym of 存じ上げません(Zonjiagemasen), there is a word 存じ上げる/ぞんじあげる/Zonjiageru which a 謙譲語(Kenjo-go) of knowing. Synonyms of 存じ上げません(Zonjiagemasen) include 知りません/しりません/Shirimasen which means one is not being able to recognise the existence or occurrence of things as they are or 存じかねます/ぞんじかねます/Zonjikanemasu which means one can’t know.
Examples of 存じ上げません(Zonjiagemasen)
Kare no namae wa zonjiagemasen
I don’t know his name.
Ano hito no renrakusaki wa zonjiagemasen node chokusetsu gokakunin kudasai
I don’t know his contact details, so please ask him directly
Taihen moushiwake arimasenga, watashi wa sukoshi mo anata no koto wo zonjiagemasen
I'm very sorry, but I don't know you one bit.
Definition of わかりかねます (Wakarikanemasu)
わかりかねます (Wakarikanemasu) is a polite way of saying "I don't understand" or "I don't know.”. The phrase わかりかねます (Wakarikanemasu) is a combination of わかる/Wakaru which means to understand and かねる/kaneru which means difficult to do something, creating the meaning difficult to understand. It has a similar meaning to “I’m not sure” in English. When you use negative expressions such as わかりません(Wakarimasen) or 知りません(Shirimasen) which means “I don’t know”, it will sound a bit strong, so use わかりかねます (Wakarikanemasu) instead which will give a softer impression. Since わかりかねます (Wakarikanemasu) is an honorific, it can be used in business situations with your boss and clients. However, depending on the situation, it may make other people feel annoyed or give the impression that you are being rude, so it is important to use it in appropriate situations.
When written in kanji, it can be written in either「分かりかねます」「解りかねます」 or 「判りかねます」but 「分かりかねます」 is the most commonly used one.
Example of わかりかねます (Wakarikanemasu)
Anata no ito ga wakarikanemasu
I'm not sure what your intentions are.
Ima wa wakarikanemasuga, kakunin shidai renraku itashimasu
I'm not sure right now, but I'll let you know as soon as it's confirmed.
Watashi dewa wakarikanemasu node, tanto no mono wo oyobi itashimasu.
I don't know what's going on, so I'll call the person in charge.
Both 存じ上げません(Zonjiagemasen) and わかりかねます (Wakarikanemasu) are polite ways of saying “I don’t know”. If you are not sure which one to use, use 存じ上げません(Zonjiagemasen) and use わかりかねます (Wakarikanemasu) when you want to express yourself more softly.