What is the difference between ～気もする and ～気がする?


I encountered the following line in a visual novel.

_Context: Somebody says that a person is very expressive (in countenance) by
using the word 表情豊か. Then, somebody else says the following._

> 豊かとはちょっと違う気もするけど

I am assuming that ～気もする is ～気がする with も substituted. I was unable to find a
question (or answer) here covering any change in meaning when using も. I was
also unable to find any explanation of 気もする (but I did find many for 気がする).
However, according to [this question's
answer](https://hinative.com/en/questions/343731), it appears that using も, as
opposed to が, expresses "multiple opinions." **If this is the case, then how
is the above line different than the following?**

> 豊かとはちょっと違う気がするけど (I feel that it is a little different from rich. [uncertain
> tone])

I am guessing that も makes the statement more emphatic.




> 豊かとはちょっと違う気 **も** するけど

**も** in the above phrase is a particle that means _also; in addition; as
well_. I think it is exactly what is said in your quotation: _according to
this question's answer, it appears that using も, as opposed to が, expresses
"multiple opinions."_

I'll show you easy examples as:

>   1. この果物｛くだもの｝の味｛あじ｝は、甘｛あま｝い気｛き｝ **が** する _The taste of the fruit is
> sweet_.
>   2. この果物｛くだもの｝の味｛あじ｝は、甘｛あま｝い気｛き｝ **も** する _The taste of the fruit is not
> only sweet, but also ..._
>

When the taste of the fruit is sweet, you could express the taste definitely
by phrase 1.  
On the other hand, when the taste of the fruit is almost sweet but a little
sour, you can't use phrase 1, so you would say by using **も** like phrase 2.
In this case, phrase 2 implies この果物｛くだもの｝の味｛あじ｝は、甘｛あま｝い気｛き｝ **も** する、
そして、少｛すこ｝し酸｛す｝っぱい気｛き｝ **も** する。

As the conclusion, the given phrase 豊かとはちょっと違う気 **も** するけど implies that
speaker can not definitely say only 豊か _richness_ by using も instead of が.

## Another reason to use "も" instead of "が"

I am going to talk about another reason why Japanese people use the expression
"気もする" that is used in the given phrase with "豊かとはちょっと違う **気もする** けど" more
frequently than the theoretical reasons.

I mentioned above that "甘い気もする" is not an assertive expression than "甘い気がする".
Naturally, if you are fully confident in what you are going to say, namely if
you feel the taste of the fruit is sweet without doubt, you would say
assertively "甘いと思う" or "甘いです". If you say something in this way, I think it is
common in the world that people who do not think so will object to it.  
A: "I think like this."  
B: "No, I don't think so."  
However, in Japan, although what is right (/correct) and what is wrong
(/incorrect) is naturally important, the sense of value of " ** _wa_ 和**" or "
_ **harmony**_ " is sometimes more important than to assert the rightness or
correctness in order to avoid conflict among the people in the society.
Although this value is said decreasing these days in comparison with the old
days, it still seems to be common among Japanese people. "[和]{wa}" seems like
a good ingenuity that the predecessor invented in order to avoid such a
confrontation. Therefore, Japanese people sometimes use expressions such as
"気もする" even if their true intention is to say "気がする", so it is annoying but
prudent to know that there is a case where speaker avoids conflict with the
opponent by saying so.




> 豊かとはちょっと違う気 **も** するけど

**も** in the above phrase is a particle that means _also; in addition; as
well_. I think it is exactly what is said in your quotation: _according to
this question's answer, it appears that using も, as opposed to が, expresses
"multiple opinions."_

I'll show you easy examples as:

>   1. この果物｛くだもの｝の味｛あじ｝は、甘｛あま｝い気｛き｝ **が** する _The taste of the fruit is
> sweet_.
>   2. この果物｛くだもの｝の味｛あじ｝は、甘｛あま｝い気｛き｝ **も** する _The taste of the fruit is not
> only sweet, but also ..._
>

When the taste of the fruit is sweet, you could express the taste definitely
by phrase 1.  
On the other hand, when the taste of the fruit is almost sweet but a little
sour, you can't use phrase 1, so you would say by using **も** like phrase 2.
In this case, phrase 2 implies この果物｛くだもの｝の味｛あじ｝は、甘｛あま｝い気｛き｝ **も** する、
そして、少｛すこ｝し酸｛す｝っぱい気｛き｝ **も** する。

As the conclusion, the given phrase 豊かとはちょっと違う気 **も** するけど implies that
speaker can not definitely say only 豊か _richness_ by using も instead of が.

## Another reason to use "も" instead of "が"

I am going to talk about another reason why Japanese people use the expression
"気もする" that is used in the given phrase with "豊かとはちょっと違う **気もする** けど" more
frequently than the theoretical reasons.

I mentioned above that "甘い気もする" is not an assertive expression than "甘い気がする".
Naturally, if you are fully confident in what you are going to say, namely if
you feel the taste of the fruit is sweet without doubt, you would say
assertively "甘いと思う" or "甘いです". If you say something in this way, I think it is
common in the world that people who do not think so will object to it.  
A: "I think like this."  
B: "No, I don't think so."  
However, in Japan, although what is right (/correct) and what is wrong
(/incorrect) is naturally important, the sense of value of " ** _wa_ 和**" or "
_ **harmony**_ " is sometimes more important than to assert the rightness or
correctness in order to avoid conflict among the people in the society.
Although this value is said decreasing these days in comparison with the old
days, it still seems to be common among Japanese people. "[和]{wa}" seems like
a good ingenuity that the predecessor invented in order to avoid such a
confrontation. Therefore, Japanese people sometimes use expressions such as
"気もする" even if their true intention is to say "気がする", so it is annoying but
prudent to know that there is a case where speaker avoids conflict with the
opponent by saying so.

