らむ / けむ / まし: Finer Conjecture

Once you know the workhorse conjecture む, classical Japanese offers three specialists that slice "probably" into finer times and moods: らむ points at the present you cannot see, けむ points at the past, and まし builds the counterfactual — "had things been otherwise, it would have been…." These collapsed long ago into modern だろう, ただろう, and 〜のに, so you will rarely need to produce them. But they surface every time a waka is quoted — in the New Year かるた reading of the 百人一首（ひゃくにんいっしゅ）, in a classical prose passage, in a literary allusion — so the goal here is different from the other classical pages: recognition, not production. Knowing that らむ / けむ / まし all flag "conjecture" is enough to follow a recited poem without decoding every syllable.

らむ — "probably … right now, out of sight"

らむ attaches to the 終止形（しゅうしけい） (for ラ変 verbs, the 連体形) and conjectures about the present that the speaker cannot directly observe. Its two most common jobs:

• 現在推量（げんざいすいりょう） — "is probably …-ing now (somewhere I can't see)." My friend is probably sleeping by now.
• 原因推量（げんいんすいりょう） — conjecture about the cause of a visible present fact: "why is it that…, I wonder?" This is the sense you meet most in poetry.

The 原因推量 らむ is the beating heart of one of the most beloved poems in the 百人一首, recited aloud every New Year:

The poet sees the blossoms falling; らむ asks, wonderingly, why they should scatter so unquietly on so peaceful a day. Translate 散るらむ as a flat "the blossoms fall" and the poem's entire ache — the puzzled tenderness — evaporates.

けむ — "probably …ed / must have …ed"

けむ attaches to the 連用形（れんようけい） and is らむ's past-facing counterpart: conjecture about what happened, or why it happened, back then.

• 過去推量（かこすいりょう） — "probably …ed, must have …ed."
• 過去の原因推量 — "why did it …?, it must have been because…."
• 過去の伝聞・婉曲 — "…ed, so they say."

Be honest with yourself about frequency: けむ is genuinely rare, even inside classical texts, and you will almost never need to write it. Its value is recognition — when you spot 〜けむ, read "must have …ed / I suppose …ed," and move on.

まし — the counterfactual "if things were otherwise"

まし attaches to the 未然形（みぜんけい） and expresses the mood English handles with "would have": an imagined world contrary to fact, or a hesitant, half-formed deliberation.

• 反実仮想（はんじつかそう, counterfactual) — classically framed 〜せば…まし or 〜ましかば…まし: "had it been …, it would have been…" (but it wasn't).
• ためらいの意志（hesitant deliberation) — "should I …, I wonder?" as in いかにせまし ("what on earth should I do?").
• 実現不可能な希望 — a wish known to be impossible.

The counterfactual frame is worth memorizing as a shape: the condition takes せば or ましかば, and the consequence takes まし.

Read the machinery: なかりせば ("had there been none") sets up the impossible condition, and のどけからまし ("would be tranquil") delivers the impossible result — and the unspoken twist is that, because blossoms exist, the heart is in fact never at peace. That is 反実仮想 in its purest form.

Where they went: だろう, ただろう, のに

None of these three survives as a productive form in modern speech; each folded into an ordinary modern equivalent. This table is your practical decoder:

The feeling of まし is very much alive, even though the form is gone — modern 〜のに and 〜ばよかった carry exactly its wistful, "if things were otherwise" ache.

The distinguishing insight: aim for recognition

The other classical auxiliaries earn their keep in modern Japanese — む as 〜う・よう, べし as 〜べき. らむ, けむ, and まし do not; they are the exact tier of grammar a modern reader rarely produces but reliably meets whenever poetry is quoted. That is not a reason to skip them — it is a reason to calibrate your effort correctly. You do not need to conjugate らむ; you need to hear it in 花の散るらむ and know it means "why do they fall, I wonder." Set your target at following a recited waka, and these three become easy: three flavours of the same wondering conjecture — present, past, and counterfactual.

Common mistakes

The せば…まし frame is contrary-to-fact. Read it as "had it been … it would have been," with the real world being the opposite.

Key takeaways

• らむ (→ 終止形): present conjecture about the unseen or the cause of a visible fact — "…now, I wonder / why…?" (花の散るらむ).
• けむ (→ 連用形): past conjecture — "must have …ed" — genuinely rare; a recognition target.
• まし (→ 未然形): counterfactual, framed せば／ましかば…まし — "had it been …, it would have been…"; also hesitant "what should I do?" (いかにせまし).
• They collapsed into modern だろう / ただろう / 〜のに; the counterfactual feeling lives on in 〜ば…のに and 〜ばよかった.
• Aim for recognition: hearing "conjecture (present / past / counterfactual)" is enough to follow a recited waka — you rarely need to produce these.