EXACTLY! This should be pinned somewhere tbh. Noticing these patterns helped me tremendously in my studies.
I once read an article that claimed you should not pay attention to these patterns as they “don´t work”, there are “exceptions” and calling this trick even dangerous to learn. Which is of course complete bollocks as there are few exceptions and most of the time you can make an educated guess.
If you want to know more about these verbs you can check out Tofugu‘s article on it:
This one follows the general rule: in a verb that has “a” and “e” forms, the “a” is intransitive and the “e” is transitive.
下がる, 下げる
閉まる, 閉める
集まる, 集める
始まる, 始める
止まる, 止める
etc…
This is hard to grasp at first.
The reasoning that worked for me was this:
Intransitive:
If the verb is affecting the subject and the subject is still the one doing it, then it must be intransitive.
e.g. “I stopped” This is intransitive because I is the one who is affected by the stopping and the one doing it.
Transitive:
If the verb is being performed by the subject, but is affecting something else, then it is transitive.
e.g. “I ate bacon” I, like last time, is performing the verb, but this time it is not the one being affected by it (being eaten). Therefore, it takes an object and that object is having the verb done to it. This would be a transitive verb.
I think once you understand them in English, it gets a lot easier to think about it in Japanese.
As others have said, it can be difficult to understand for English speakers because we communicate the difference between transitive and intransitive through word order and whether there’s an object. So, it can seem odd that other languages make this distinction via inflexion.
I hope this helped!
I actually think this article, while helpful in a lot of ways, is a bit misleading. When I first started out I took the rules on there at face value and got shot down in another thread here with many, many exceptions. 
Some of the “laws” as stated don’t work in all cases because there is a lot of nuance to the way they need to be explained and I don’t think it does it very well. I’m not saying the patterns are wrong - just that they’ve been oversimplified.
The only one that really works (in my studies so far) is the First Law: All verbs ending in す (-su) are transitive.
The Second Law is only true for verbs forming transitive-instransitive pairs, and only then if they don’t also follow the pattern of the Third Law. You see what I mean? It starts to get really messy and I’m not sure how helpful it is when it starts to get into all these exceptions.
Similar to other posters in this thread I’ve usually just taken the general approach that 90% of verbs ending in an eru sound are transitive so if you are stuck on a verb pair you are going to be able to make a fairly decent guess.
What do you mean, only then if don’t follow the pattern of the Third Law ? Do you have any example ? From what I know, the aru pattern meaning the verb is intransitive work 100% of the time in transitive-intransitive pair, and about 90% outside. It’s not messy at all, in verb pair す=transitive, aru=intransitive is always true, everything else is unreliable.
That is kind of my point. You have to know that the word is in a verb pair (which CureDolly doesn’t make very clear), otherwise if you’re seeing a word for the first time it can be hard to tell sometimes. Those rules aren’t wrong but they have a specific application. I find it starts to get too fiddly but that’s just me.
割る waru - to divide (transitive - ends in /aru/ sound)
割れる wareru - to be divided (intransitive)
It’s a verb pair but the Third Law here (u → eru) overrides the Second. If you saw 割る in isolation it becomes trickier.
Seeing a verb in the wild is the easiest way to tell, no? You can just see how it’s used, whether it’s transitive or intransitive.
Fair point. Although the way the word is tested here on WaniKani is always in isolation so maybe it’s more a problem of getting your reviews right!
So there is an exception ! Thanks for finding it !
I guess, I will have to retrograde the aru rule to 99% efficiency in verb pairs
And checking this list of pair I can also spot 張る haru (transitive) / 腫れる hareru (intransitive). But it’s interesting though, I never really thought before of 張る and 腫れる as a verb pair. 
Sure, agreed, when it’s the first time I always check a dictionary. But often, at least for me, when I learn a new verb pair, there is stage where I start to remember that those two verbs are linked but I’m confused about which one is which and at that time the two す/aru guideline works well.
While I agree that patterns are more often helpful than dangerous, I’d just like to highlight that in this particular case, that article has a bit of a point because these patterns are often taught using ‘transitive-intransitive pairs’, and the issue then is that some people come away from it thinking that -eru verbs are always transitive when they’re in fact also intransitive in other pairs. The reason is that there are two main ‘pair patterns’:
-aru intransitive/-eru transitive
-u transitive/-eru intransitive
That doesn’t invalidate the patterns mentioned above, but depending on how you learn the patterns (e.g. if you’re taught to see them as part of these pairs), you may get confused if you’re not aware of the other patterns. That’s all.
@Mariem Would you be willing to share a few examples of the words in Japanese that you’re having trouble with? I agree that requiring the addition of words like ‘something’ or ‘someone’ would definitely make the ‘transitive’ nature of a verb more obvious, but the impression I’m getting is that the idea of ‘transitivity’ is confusing even in English. For example (do tell me if I’m wrong), but
‘to be released’ cannot possibly be transitive, precisely because of what you said: a transitive verb requires an object. This doesn’t. Could this be the passive voice as well? Yes, and there are sometimes overlaps between the passive voice and the intransitive. The main difference, I think, is a difference in emphasis: the passive voice implies an external cause, as in ‘the bottle was spun’ (i.e. someone did it), as opposed to ‘the bottle is spinning’ (i.e. the statement focuses on the movement regardless of how it started).
For the sake of making things easier to remember, I’d suggest considering this:
‘Trans-’ means ‘across’ as a prefix. There’s an idea of moving across or transfer. In the most basic, physical sense, a transitive verb involves one thing moving another (i.e. transfer of… momentum, if you like?). An intransitive verb involves something moving itself (i.e. no transfer of momentum). I hope that analogy helps.
Sure, I’ll go into a bit more detail:
These verbs are all intransitive, just like ある, which means that these verbs do not (cannot) take the particle を. This is because they are actions that the “subject” of the sentence (which is prescriptively marked by が, but may be specified by は, or else omitted entirely and left implied in Japanese) simply does on its own, without any transitive “target” (“direct object,” marked by を).
In direct contrast to that, this list here…
…is entirely transitive, like する is. It’s understood that for each of these verbs, [ _____を] is a part of the sentence. For example, 宿題を出してください means “please hand in (your) homework,” and even if you leave out 宿題を, it would still mean “please hand (it) in” because the fact that 出す is transitive means that something absolutely must be the “direct object” of the phrase, even if we leave it unsaid.
Here are a few more examples of how transitivity is understood, and what can happen if you use it incorrectly. 開く (あく) and 開ける (あける) here both mean “to open,” but 開く is intransitive and 開ける is transitive:
Correct:
○ ドアが開く。 → “The door opens.” (nothing is implied)
○ ドアを開ける。→ “(I / we) open the door.” (the sentence’s “subject” is implied)
○ 私(は・が)ドアを開ける。→ “I open the door.” (nothing is implied)
○ 私(は・が)開ける。 → “I open (the door).” / “I open (it).” (the sentence’s “direct object” is implied)
Incorrect:
× ドアを開く。 → This is like saying “fall the ball,” “rise your hand,” or “die the enemy”
× ドアが開ける。→ Technically, this is grammatically correct, but it’s strange since it’s saying “the door opens (something),” with (something) being implied since we haven’t specified what’s being opened (because we have no を in the sentence)
Note:
ドアが開ける would actually probably be read as ドアがひらける, which would even be normal / natural since ひらける is intransitive, but that’s more of an issue of there being too many verbs using the 開 kanji than anything else
A beginner mistakenly saying「ドアがあける」instead of「ドアをあける」or「ドアがあく」would still be strange. EDIT: Or, it could be interpreted as the potential of 開く, which would make the sentence mean “The door can be opened / is openable” instead of “the door opens.”
This is so generous of you to share. Thank you so much! I am going to print this out, as someone suggested below, and save it.
thank you so much for taking the time to do that!! I totally appreciate it.
(now for some studying. I MUST sort this business out)
Also note that transitive/intransitive doesn’t totally match the japanese definition of other-move/self-move verbs (他動詞 / 自動詞). There are situations where a self-move verb takes an object or a other-move doesn’t, which is confusing as hell.
Can you expand on what the difference is?
I’m pretty sure that’s one of Cure Dolly’s things she preaches.
Indeed. Check her explanation before I totally butcher japanese grammar in trying to rephrase it.
But basically, it’s her justification for not using “transitive” and “intransitive” when talking about the Japanese verbs.
Japanese people teach English transitive and intransitive verbs by using the terms 他動詞 and 自動詞, so I don’t personally think there’s much reason to overthink it.
Just like how a “verb” in English and a 動詞 in Japanese have different properties in the two languages (different ways of using them, different conjugations, etc), doesn’t mean we can’t still call 動詞 verbs when we’re speaking English and discussing Japanese.
Forgive me if she explains it in a different video but in “Lesson 15: Transitivity- the 3 facts that make it easy. Transitive/intransitive verbs unlocked” she seems to argue that 従う, a 自動車, is transitive because the English translations for it, to obey and to follow, are transitive. I see this as more of an issue with the translation than 従う actually being transitive.