There are several synonyms that can be used in place of the phrase 'without knowledge'. Some of these synonyms include 'ignorant', 'uninformed', 'clueless', 'unaware', 'unenlightened', 'unschooled', 'untrained', 'inexperienced', and 'naive'. The use of these synonyms will depend largely on the context in which they are being used, but they all communicate a lack of knowledge or understanding about a particular subject. It's important to note that while these words all convey a similar meaning, they each have their own connotations and nuances that may affect the overall tone and message of the sentence.