As a pseudonymous blogger and defender of the idea of anonymous and pseudonymous writing, I believe that you shouldn't need to use your real name in order for your ideas to be taken seriously. However, pseudonymity can be abused. When this happens it crosses the line and becomes sockpuppetry. But where exactly is that line? As I see it there's one very simple rule that anyone using a pseudonym should respect: Don't lie. Or to elaborate: Don't make false claims about your identity - explicitly or implicitly. You might say: but "Neuroskeptic", you yourself are claiming to be someone you're not, with your pseudonym. But I don't think I am. "Neuroskeptic" is obviously not my real name. It's clearly a pseudonym, and so anyone reading something written by "Neuroskeptic" will assume that the author is someone who's chosen to write as "Neuroskeptic". Which is true. That's what I am. So I'm being perfectly transparent. However, had I chosen a 'realistic' pseudonym like "Peter Sounick", or whatever, then I'd be being deceptive, because this appears to be an actual name, and obscures the fact that I'm using a pseudonym. There is an implicit understanding that a real-looking name is real. (There are exceptions: novelists and actors often adopt real-looking pseudonyms. I think these are not deceptive, but only because they're a normal and expected practice in those contexts.) A realistic pseudonym is bad enough, but it's outright lying if you embelish your real-sounding pseudonym with a fake address (as in this case) or a fictional biography (as in "David Rose", sockpuppet of British journalist Johann Hari.) But a deceptive pseudonym is only one of many ways to become a sockpuppet. Even an 'obvious' pseudonym can be deceptive in certain contexts. For example, I believe that one shouldn't comment 'in the third person' on ones real identity. This would break the implicit understanding that we talk about ourselves in the first person - that if I am talking about myself, I do so openly. Breaking this rule, and commenting on a story concerning himself under the pseudonym "Paul", just got notorious academic fraudster Diederik Stapel branded a sockpuppet on the Retraction Watch blog - and rightly so.
Likewise, it's deceitful to use two or more different pseudonyms in the same conversation. This would go against the understanding that within a given context, each person has one identity. To use multiple pseudonyms in the same context - or indeed a pseudonym in addition to your real name - could create an illusion of consensus. This is the rule that I most worry about breaking myself. My real identity, after all, has all the same opinions as Neuroskeptic. So I have to make an effort to ensure that I don't end up stating my views twice. Finally, lying about ones background is obviously wrong. Given that I am a British man, if I claimed that "Neuroskeptic" was the pseudonym of a Syrian lesbian, I'd be lying. I would also be lying if I denied being a neuroscientist, because I am one. I think I would also be dubious if I omitted to mention some relevant aspect of my identity - if I owned stock in a company and then commented on that company, without disclosing my stake, say. But that would be equally deceptive if I did it under my real name. Undeclared conflicts of interest are not specific to pseudonymous comment.