Lesson 32: Just with だけ, のみ, ただ, ばかり, しか
だけ, のみ, ただ, and ばかり are variations of "just" or "only". しか is similar, but it has negative polarity.
だけ means "just so", in terms of amount. It acts like a particle.
俺だけ行く I'm the only one going (Metaphorically: "Only I will go")
俺だけじゃないよ "It's not just me though."
のみ is like a less colloquial だけ that shows up in different grammar patterns.
ただの人間が存在するのみです There are only mere humans.
ただ is related to the idea of "just so", but it focuses on emphasis. Except for specific constructions (like ただの), taking a true sentence and adding ただ will result in another true sentence; this is not true of だけ or のみ.
僕はただ子供だよ I'm just a kid.
One construction where ただ is not just about emphasis is ただ一つ, where 一つ
ただ一つ問題がある There's just one problem.
たった is basically a variant of ただ.
ばかり is yet another "only" word. Like だけ and のみ, it changes what the sentence means. It can also be pronounced ばっか or ばっかり. ばかり focuses on everything falling into this statement, whereas だけ and のみ focus on things falling outside of this statement being false. ばかり is sometimes translated like "He always X" or "The only thing left to do now is X". ばかり cannot be used in negative environments.
犬ばかりだ It's nothing but dogs.
ばかり can also mean "just" in the time sense, usually with the past tense.
ばかり来たよ
しか is used with negative statements to say that the negative statement is true of everything except for what is tagged with しか, like "but".
僕しかいない Nobody but me is here.
Be careful, though, because しか can occur in grammar fossils like いつしか where it isn't a "but/except" word at all.
彼はいつしか行ってしまった He ended up leaving before anyone noticed.
Sometimes (but rarely), しか is used outside of complete statements.
「みんな来たの？」 「うん、彼しか」 "Did everyone come?" "Yeah, except him."
The difference between しか and だけ in negatively-polarized statements is basically the reason that polarity exists.
僕しかいない Except for me, people are not here. (I'm the only one here.)
僕だけいない Just me, I am not here. (I'm the only one not here.)
しか can be substituted with っきゃ.