Hi everyone! I was wondering if there is a way to easily tell the difference between transitive and intransitive verbs just by looking at them, not at the particles surrounding them? Like is there any regularity or logic in the way transitive/intransitive verbs are formed? I would really appreciate any tips or tricks on how to differentiate between them or even how to memorize some of them(mnemonics are appreciated).
If it's a transitivity pair verb ending with -す (like 出す、返す、起こす、落とす、壊す), it's transitive just like する is.
If it's a transitivity pair verb with an -ある sound (like 終わる、始まる、変わる、閉まる、当たる). These are intransitive just like ある is intransitive.
The "-eru usually being transitive" tendency you've mentioned is just a byproduct of lots of verb pairs being -aru/-eru (e.g. 始まる・始める、終わる・終える、変わる・変える、閉まる・閉める、決まる・決める). So, if you hear an -eru verb and you don't know (or can't remember) what its partner verb is, "-eru being transitive" is likely a safe guess, but there's no guarantee.
Of course, if neither verb in a pair has an -eru or -す ending, then there's no way to confidently guess the transitivity. But, these are still VERY reliable patterns to know for when they do apply :)