Why only one Designer

The topic here is about intelligent design, and why Intelligent Designers propose a single designer and not many.It is not about the a scientific and/or logical analysis of the Theory of Evolution, as compared to anything else.. Everyone try to stay on the subject, which is ID.Also, note that a participant is not obliged to respond to all replies he gets. This is more important for creationist/IDers, since they are the ones receiving multiple replies to the same posts. They cannot always answer back as it can become time consuming, amongst other things. In those cases that another participant does not reply to a post you would have liked a reply, bring it back into the discussion in a comprehensive manner and not an accusive manner. This will help in the overall discussion (all this applies only if your reply was on topic, everyone here are grownupes and can judge if the discussion is staying on topic)