The historic Reformed view of Sola Scriptura:
Westminster Confession of Faith 1.6: The whole counsel of God concerning all things necessary for his own glory, man’s salvation, faith and life, is either expressly set down in Scripture, or by good and necessary consequence may be deduced from Scripture: unto which nothing at any time is to be added, whether by new revelations of the Spirit, or traditions of men. Nevertheless, we acknowledge the inward illumination of the Spirit of God to be necessary for the saving understanding of such things as are revealed in the Word: and that there are some circumstances concerning the worship of God, and government of the church, common to human actions and societies, which are to be ordered by the light of nature, and Christian prudence, according to the general rules of the Word, which are always to be observed.
R. Scott Clark on the switch from Sola Scriptura to Biblicism:
“Under the influence of Anabaptist radicalism, which swept across and transformed American evangelicalism in the 19th century (the causes of which are the subject of another post) led it away from the Reformation understanding of sola Scriptura to a different doctrine: biblicism or the attempt to understand Scripture by one’s self and by itself, i.e., in isolation from the history of the church and in isolation from the communion of the saints. In biblicism the interpreter, not Scripture, becomes sovereign. Historically biblicists, although they boast about their devotion to Scripture, are actually devoted to the supremacy of reason. As someone, somewhere said, “All heretics quote Scripture.” It is one thing to quote Scripture but it is another to read it well and to interpret it properly.”