In defense of is a common phrase which is used to justify or support a particular viewpoint or argument. However, there are several synonyms that can be used to convey the same meaning. For instance, "to support" or "to uphold" are excellent alternatives that indicate a person's commitment to their position. Similarly, "to advocate for" or "to champion" could be used to indicate a person's desire to defend their viewpoint. In addition, "to justify" or "to explain" are also synonyms that could be used to defend a position while indicating that one has a logical reason for their stance. Overall, it's essential to choose the appropriate synonym that accurately reflects the meaning in an argument.