Probability and conjecture: "darou" and "deshou"

The endings だろう (darou) and its polite counterpart でしょう (deshou) are used in Japanese to express probability, speculation, or to make conjecture. They roughly correspond to "probably," "I think," or "don't you think?" in English. When spoken with a rising intonation, they invite agreement from the listener.

To use these forms, simply attach them to the plain forms of verbs, adjectives, or directly to nouns. For example: ame ga furu deshou (it will probably rain), yasui darou (it's probably cheap), gakusei darou (he's probably a student). For na-adjectives and nouns, omit the final copula da before attaching darou/deshou.

A common mistake is using the copula だ (da) or です (desu) directly before darou/deshou (e.g., saying da darou or desu deshou, which is redundant and incorrect). Another error is using these endings when you are absolutely certain of a fact; they should only be used when there is some level of speculation or when politely softening a statement.