情態副詞是閩南語中表達情態最重ㄑ要的詞類之一。語意上情態副詞所傳達的是說話者對句子命題內容的觀點與心態，包含說話者對命題「真偽」(alethic)、「認知」(epistemic)、「願望」(boulomaic)、「義務」(deontic)、「評價」(evaluative) 的態度以及對其「可能性」(possibility)、「蓋然性」(probability)、「必然性」(necessity)等判斷。這些是根據語意所做的，若依句法特徵來分析，情態副詞通常都與情態動詞連用﹐而且幾乎都與固定的情態動詞相搭配。再就句法結構上的出現分布而言﹐情態副詞大致上可分為三種；即義務性情態副詞、認知性情態副詞、與說話者導向情態副詞。這三種情態副詞都有一定的排列順序，即說話者導向情態副詞先於認知性情態副詞﹐而認知性情態副詞則先於義務性情態副詞。以往的研究對於這些情態副詞的詞序都從其修飾範域的大小來解釋﹐其實情態副詞與情態動詞之間也有著十分密切的關係。副詞一般都分析為動詞的附加語，因而與動詞的關係甚為密切，也就是說，情態副詞與情態動詞通常相伴出現。根據Travis 的副詞認可原則， 副詞是由於詞組結構上無法投射成為最大投射（maximal projection），亦即無法經由「主謂關係」（predication）或「論旨角色指派」（theta-role assignment）得到適當的認可，所以必須經由這些副詞所加接的詞組中的主要語的屬性來認可。因此，一般情狀副詞是由動詞組的主要語V°的屬性來認可、義務類的情態副詞由述語動詞組的主要語Pr°的屬性來認可、認知類的情態副詞由屈折詞組的主要語I°的屬性來認可、而以說話者導向的言談情態副詞則由補語連詞組的主要語C°的屬性來認可。這種認可原則不但可以合理地詮釋情態副詞為什麼一定要依賴句中其他情態詞，如情態動詞，才能出現，並且也直截了當地闡述各類副詞在句中子出現的線性次序（linear order）。

The traditional way of categorizing modal adverbs in Taiwan Southern Min is by means of semantic properties, such as the speaker's alethic, epistemic, boulomaic, deontic, or evaluative attitude towards the sentence proposition or the speaker's conjecture of the sentence possibility, probability, or necessity. This categorization is often diverse and captures little generalization. This research proposes a syntactic analysis based on the distribution and licensing assignment of modal adverbs. There are three types of modal adverbs: speaker-oriented, epistemic, and deontic adverbs, and they always appear in the order of the speaker-oriented type precedes the epistemic type and the epistemic type precedes the deontic type in a sentence. According to Travis (1988), adverbs are a defective construction due to their lack of maximal projection and therefore cannot be licensed via theta role assignment or predication. They must be licensed by the head to which they are adjoined. Based on this, we propose that in modal adverbs, the deontic modal adverb is licensed by the head of PreP (Pre°), the epistemic modal adverb licensed by the head of IP (I°), and the speaker-oriented modal adverb by the head of CP (C°). With this licensing principle and the modal adverb categorization, not only the co-occurrence restriction between the modal adverbs and their particular heads but also the linear order of these three types of modal adverbs in a sentence can be accounted for in a systematic way.