This lesson will focus on grammar points that indicate that something is the "opposite" of something else.
逆 in its simplest understand is a noun or adjectival noun (with the particle の) that can be translated as "reverse/opposite." This is especially so when referring to direction, psychology in which it is translated as "converse," and math in which it is translated as "inversion."
That is exactly why I did the opposite of the instructions.
If you stumble, do the opposite of what you normally would.
The converse of a proposition in which "p⇒q" is "q⇒p," with the hypothesis and conclusion flipped.
In an inverse relationship, when one number goes up, another number goes down.
Conversely speaking, 1 out of 7/8 patients have passed the extent to which surgery can be performed, and so anticancer drugs + radiation treatment are prioritized.
Grammar Note: Note that 逆に is the adverbial form of the word.
Even though it played white noise to fall asleep, it conversely made me unable to sleep.
As a noun and adjectival noun (with the particle の or な※) 反対, means "the opposite" as in the essence/reality of things. It can also translate to "dissent/opposition/antagonism." It can even be used as a する verb to mean "to oppose."
The opposite of white is black.
To say the opposite thing of what you're feeling.
It's a vague opinion on whether it's in favor of or against it.
Many of the nation's citizens are against reforming the constitution.
There is also a deeper difference between the two. 反対 is appropriate when the correct direction/course of action isn't actually set in stone, but 逆 can indicate that the direction/course of action is opposite of what they should be.
This allows for 逆 to be incorporated in other compound words with the meaning of "opposite."
I drove down the wrong way down on a one-way street.
Please ride the bus that goes the opposite direction.
Let's overcome adversity.
The opposite effect can happen, so it's important to take caution.
To counterattack the enemy army.
He also has the exact opposite reputation of being a strict store manager from certain people.
When "side/affiliation" is intended by "opposite," 反対 is used in compounds. Take for example 反対側 (the opposite side), 反対派 (opposition wing), 反対者 (opponent/adversary), etc.
Of course, dating someone with the exact opposite personality as you is not easy.
The opposition was the majority in the vote for independence.
To put pressure on the opposition force.
～とは逆に & ～とは反対に
～とは逆に and ～とは反対に are synonymous phrases which indicate that Situation Y is the opposite of one's expectation (Situation X). The former is more common in the spoken language whereas the latter is more common in the written language. However, there is nothing stopping you from using either in any given situation. It's just that ～とは反対に has a more serious tone.
Completely opposite of my little sister who is meticulous, I'm sloppy in ways.
They say that marriage is the opposite of fever in that it starts with feeling hot, then ends in chills.
Opposite to how acupuncture needles affect the body not so deep, moxibustion is said to affect the deepest part of the body, that is one's blood.
Another difference is that the reality stated by ～とは逆に is typically viewed in a negative light or at the least as an inconvenient, complicated matter, whereas ～とは反対に is a just a firm assertion of being opposite of something else.
As for that store, opposite to how food goods are cheap, commodities are fairly expensive.
24. あの店は日用品が高いのとは【反対に 〇・逆に △】、食料品が割と安い。
As for that store, opposite to how commodities are expensive, food goods are fairly cheap.
Opposite of that, one grammar pattern may express several meanings.
In Japanese, "〇" indicates that something is "good" and "X" indicates that something is bad, but depending on the language, "X" may express something good, contrary to how it is in Japanese.
Reality ended up being the opposite of my expectations.
～反面 and ～一方（で）can both be translated into English as "on the other hand/while" and both are more commonly found in the written language (although not restricted to it). The grammatical differences between the two happen to be subtle but also telling about the contrast being made.
To see how they differ grammatically, we need to step back and view the overall sentence structures that one may find either of them. To do so, let's use the letters A, B, C, and D. A and C stand for noun constituents and B and D stand for predicates.
These two phrases overlap the most in "AはB 反面・一方（で）+ D." In this structure, A is the topic and B and D are coexisting yet contradictory situations. As for how D compliments B, in the case of 反面, D is either a not so desirable circumstance or completely unexpected at the least. In the case of 一方(で), two opposite-but-true statements about the topic are juxtaposed together.
Grammar Note: Both ～反面 and～一方（で） follows the 連体形 of predicates. With adjectival nouns, な or である may be used.
While it's strong against water, it's weak to heat.
Seth Sensei instructs his students earnestly, and while he might be short-tempered, he is tolerant.
My grandfather is hard of hearing, although his eyes and teeth are fine.
Although I believe what Kate says, I also doubt her at times.
I do believe what Kate says, but at the same time, I also doubt her at times.
Although smartphones are useful, data fees are high and battery consumption is intense.
Another difference is that B pertains to static circumstances with 反面, whereas it pertains to dynamic circumstances with 一方（で）. That's not to say there isn't any overlap between these two, but that there is a difference between viewing two sides of the same coin being completely different versus pointing out that different stuff is happening to each side. When the static/dynamic nature of B strongly tilts to either being a condition or a motion, 反面一方（で）lose interchangeability.
Particle Note: で is more likely to be used with 一方 when the more prominent the action(s) are in the sentence. Meaning, the more static the sentence, the less likely で is used with 一方, and when the sentence is too static and cannot be perceived dynamically, 一方 itself becomes unnatural.
34. 新発売の抗癌剤は、よくきく【反面 〇・一方 X】、副作用も強いらしい。
Newly released anti-cancer drugs work well, but on the other hand, their side effects are also apparently strong.
35. ケイトさんは、昼間に小さなレストランで働く【反面 X ・一方で 〇】、夜は大学院に通って歴史の研究をしている。
While Kate works at a small restaurant in the day time, at night, she goes to graduate school where she does history research.
I teach Japanese, while on the other hand, I study Catalan.
Kate works as an office lady at a small realtor in the day, and on the other hand at night, she participates in research on Korean language education as a professor.
This region has continental climate, so winter is winter with the temperature dropped below 0° pretty much every evening, and on the flip side, summer is summer with the temperature rising above 40° every day.
At that supermarket, whereas food items are cheap, commodities are expensive.
In the grammar pattern "AがB一方＋CはD," A (entity/situation) and C (entity/situation) are being compared and the predicates B and D are not restricted to the non-past. This is due to the fluidity allowed for the dynamic event (or flow of events) that
In Canada during the winter, the air dries out and the wind that blows is so cold that you feel it to your core, but on the other hand in the state of Florida in the U.S, the moist air cuts your skin a little bit, hardly ever snowing.
This winter in Canada, the air dried out and the wind that blew was so cold that you could feel it in your core, but on the other hand in the state of Florida in the U.S, the moist air cut your skin just a bit, rarely ever snowing.
The pattern "AはB反面CはD" is also possible, but it is more rigid in tone as opposed to the fluidity that can occur with the events being compared with 一方（で）.
Whereas I eat anything, my younger sister is really picky.
I eat just about anything whereas my younger sister is picky.
The fundamental difference between the two is that ～反面 indicates that B is completely contrary to A whereas ～一方(で) indicates that A and B, although different, coincide with each other, and the directionality of the sentence need not be in a negative direction.
一方 as a Noun
Unlike 反面, 一方 can also be used as a noun meaning "one direction/way/side."
Because it is a one-way here due to construction, please only pass on the other side of the road.
45. 上下の噛み合った歯のどちらかをなくすと、もう【片方 ・一方 】が伸びてきてしまう。
When you lose either tooth that bite together up and down, the other one will end up extending itself.
As for shoes, when you lose of them, the other one becomes useless.
All four sides have a wall; on one of them, there is a window with iron bars, on the other wall directly opposite of this one, there is a door, on the other remaining ones, one has a desk and the other has a bed furnished there.
Synonym Note: Synonyms of this literal version of 一方 include 片方 (one side of a pair), 片側 (own side in a directional pair) , 片面 (own side as in a certain surface). However, only 一方 and 片方 can be used with the adverb もう to get もう一方 (the other one) and もう片方 (the other part of a pair) respectively.
As Sentence/Clause-Initial Conjunctions
It is also important to note that 一方 and 反面 can both start a sentence as conjunctions in the iteration (その)一方(では) and その反面 respectively.
Grammar Note: The presence of その with 一方 is a matter of emphasis and tone. It is more likely to appear at the start of a sentence than in mid-sentence position, but even so, it is possible to start a sentence with just 一方.
As for living in the country, while it may be calm, on the other hand, there is a lack of stress.
That supermarket may be cheap, but on the other hand, the quality is not good.
Taylor is at work, meanwhile I am at home.
There are family members of the deceased who do not wish for their lost loved ones names or age to be released. On the other hand, there are also many such family members who "wish for the victims to not be forgotten."
Meanwhile, the international community is not keeping step with one another.
It is also possible to see "A一方ではB他方ではD" when detailing different aspects of the same thing. In this case, 他方 is very similar to 一方, but it can only compare two aspects. When there are several sides/aspects being compared, 一方（では) is used.
Grammar Note: If there are only two aspects being compared, 他方 is interchangeable with 一方, but it is far less common in the spoken language.
Grammar Note: その appears to place emphasis a certain "hand" (aspect), which prevents it from being naturally used with this pattern. If either is used in isolation of the other, then その can be used naturally.
As for living in the country, on one hand, it's calm, and on the other hand, there is too little stress.
Although ticket prices are expensive, conversely, gasoline prices are also high.
On the one hand, I feel like I want to start over, but another part of me wants to run away from that problem.
Problems over laws on language use are difficult. On the one hand, Russia is criticizing how Ukraine has banned its citizens from speaking in their native language (Russian) in public settings, but on the other hand, Russia is ignoring how Turkmenistan has done the same thing.
We are of the understanding that we have the environment for high-level education to be executed in our city's public preschools. On the other hand, at ### Preschool, the number of students has dropped, and next year, there will only be student attending.
It's also possible for 一方の and 他方の to modify nouns. The fundamental difference
Some people gradually age and others suddenly look old.
Also sometimes after nouns in "N + ～一方だ," seeing ～一方だ at the end of a sentence indicates a one-way trend.
The store's revenue kept declining.
Living expenses keep rising.
The situation keeps getting worse.
Nowadays, the price of masks is on the decline.