This paper discusses error analysis, which is based upon the premise that all language, even "incorrect" language, is governed by rules, and the application of such analysis to the comma splice and the fused sentence. Many students formulate erroneous theories of punctuation based on spoken-language experience or on misleading definitions; in effect, they have good intentions but use bad procedures. The paper presents six patterns to which most comma splices and fused sentences conform, indicating that teachers should avoid instruction by definitions or rules and focus instead on providing a vocabulary with which related ideas can be logically connected. (RL)