Japanese Conditionals: Ba, Tara, Nara, and To

Four ways to say if, and why they are not one word

A Japanese speaker picks a conditional on three questions asked below the level of conscious thought. Does the result follow automatically every time, or does it depend on a decision? Am I talking about a general case or about one particular occasion? And am I introducing this condition myself, or picking up something my partner has just told me? Answer those and the form is already chosen. Learners who translate the English word if pick one form and use it everywhere, which is why their Japanese sounds flat in places and breaks in others.

Keep this rough division of labour. To reports an automatic consequence, the sort that holds every time, so it suits natural laws, machines, and directions. Ba is the general hypothetical of proverbs and advice. Tara sets up one specific sequence, first this happens and then that, and dominates casual speech. Nara reaches back to what the other person said and builds a comment on it, which is why it so often opens a reply. The forms below are the easy part.

Building all four from the dictionary form

Three of the four are built from shapes you already own. Ba changes the final -u of a godan verb to -eba and swaps the ru of an ichidan verb for reba. Tara is simply the plain past form plus ra, so anyone who can say tabeta can say tabetara, and every irregular verb is covered at once. Nara attaches to the plain form with nothing added, and to a bare noun with no da. To attaches to the plain non-past form.

To: the result that follows on its own

To presents the second clause as the natural, repeatable outcome of the first. Nothing is chosen and nobody is persuaded: press the button and the ticket appears, spring arrives and the blossom opens. Because of that, to is the conditional of instruction manuals, street directions, and statements about how the world behaves. Both clauses stay in plain non-past form before to, whatever tense the sentence as a whole describes.

The restriction is absolute in ordinary Japanese: the clause after to cannot be a request, a command, an invitation, an offer of permission, or a statement of what the speaker has decided to do. Eki ni tsuku to, denwa shite kudasai is wrong, and so is ame ga furu to, ikimasen ka. Swap in tara and both sentences become normal.

Ba: the general hypothetical

Ba states a condition in the abstract. It does not commit to a particular day or a particular object, which is why it is at home in proverbs, in advice, and in sentences of the form if that is true, then this follows. It is also the form inside two patterns worth learning whole: nakereba narimasen for obligation, and the regret pattern ba yokatta, meaning I should have done it.

Tara: one specific sequence

Tara ties two events together in time on one particular occasion. First the condition is met, then the second clause happens, and the speaker is usually thinking of a real upcoming situation rather than a general rule. It is the loosest of the four in what it allows afterwards: requests, invitations, intentions, permission, and questions all sit comfortably in the second clause. That flexibility is why it is the conditional you hear most in everyday conversation.

Yokattara at the end of that list is worth keeping as a set phrase. It softens an invitation the way if you feel like it does in English, and it saves you from the blunter issho ni ikimasen ka on its own when you do not yet know the person well.

Past tara: when I did that, this is what I found

With a past-tense second clause, tara stops meaning if altogether. It reports a sequence that has already happened, and the second clause is something the speaker discovered rather than planned. This is the pattern behind a great deal of everyday storytelling, and learners tend to under-use it because it looks like the conditional they were taught to translate as if.

The second clause here must be outside the speaker's control. Ie ni kaettara, gohan o tabemashita sounds odd, because eating was your own decision, and the plain te-form sequence kaette, gohan o tabemashita is what a speaker would actually say. To can also carry this discovery reading in a narrative, as in mado o akeru to, yuki ga futte imashita, which sounds slightly more literary.

Nara: picking up what your partner just said

Nara marks the condition as given rather than supposed. Somebody has told you something, or the situation makes it obvious, and you are now responding on that basis. That is why nara so often begins a reply and why it pairs naturally with recommendations, offers, and advice. It also has a timing property the others lack: the second clause can happen before the first one, which is exactly what you need when advising somebody on what to do before a trip.

Compare the first line with Nihon ni ittara, sushi o tabemasu. The nara version advises you before you leave; the tara version describes what happens after you land. Getting these the wrong way round produces sentences that are grammatical but tell the listener the opposite of what you meant.

The request rule that decides tara over ba

Ba has a restriction of its own, narrower than the one on to but just as real. When the ba-clause is an action verb describing something the listener will do, the second clause cannot be a request, a command, an invitation, or a statement of the speaker's intention. Tōkyō ni ikeba, omiyage o katte kite kudasai is wrong; ittara fixes it. When the ba-clause is a state rather than an action, that is, an adjective, a potential form, aru or iru, or a negative, a request afterwards is perfectly natural.

Minimal pairs where the choice changes the meaning

Read each pair aloud back to back. The Japanese difference is one ending, but the English gloss changes from a rule to an event, or from before to after. That is the whole skill: the conditional is not decorating the sentence, it is telling the listener how seriously to take the link between the two halves.

The mistakes that come from defaulting to one form

• Using to before a request. Eki ni tsuku to, denwa shite kudasai is ungrammatical; use tsuitara.
• Using ba where you mean one specific occasion, which makes an ordinary arrangement sound like a policy.
• Using tara for a natural law, which suggests you saw it happen once rather than that it always happens.
• Opening a reply with tara where nara is needed, so your advice lands after the trip instead of before it.
• Forgetting that nara attaches to a bare noun: ashita nara, not ashita da nara.
• Translating past tara as if, and so missing the discovery meaning in ittara, shimatte imashita.