It seems that the two-way straw men of the stem cell debate are alive and well on the Irish Times letters page. Keith Lockitch, who seems to be a postdoc at the Ayn Rand Institute, wrote a letter the contents of which I'm guessing are pretty much here. He leaves a marvellous hostage to fortune in claiming that the embryo is not quite human.

I'm always astounded at the arguments, generally trotted out by reactionary sorts, that some dreadful comment or other is to be defended on freedom of speech grounds. I suppose it's a convenient strategy for the bullshitter. You know, why defend the indefensible when you can take umbrance at people questioning your freedom to speak? Best to ignore the fact that they're generally not questioning your entitlement to speak. They're generally questioning your honesty and your manners.

But still, the claim to a right to speech is fundamentally correct even if it's generally invoked by people who don't really care whether it's correct or not. One doesn't go around saying that people shouldn't be allowed say things simply because they're offensive. To be a little bit Millian, best to get it all out there, eh?

The serious problem with the 'free speech' distraction is that it tends to be used where no free speech exists. Although we may have a fundamental right to free speech, it's not an inalienable right. We can legitimately sign it away on a daily basis. Most notably, people's signing an employment contract either explicitly or implicitly involves their constraining their speech rights. In my profession, I can't start telling you what I think of my students, or what they got in their exams, or - as is the case in most jobs - my opinions of my colleagues, or myriad other things. If I did speak my employer would be well within their rights to fire me. I have contracted to remain silent where my private thoughts contradict a range of my employer's interests.

Of course, I can break the rules, but if I value my private thoughts so much that I can't abide by those rules, then I really ought to resign.

Well, you can see where I'm going with this. There is a ministerial code of conduct in Northern Ireland. Ministers sign it. And yet, when clever Ian Paisley Jnr announced last month that he finds what homosexuals get up to repulsive (why is it that some people spend so much time thinking about gay sex?) people trot out the free speech defence. David Vance asked if it is a crime for Paisley to say what he said, as if that's the question. Sam Hanna leaves a comment on Slugger attacking the 'bigots' that deny Paisley his rights to free expression. And on it goes. The debate came up again yesterday on Slugger, hence this post.

But this isn't about shutting down free speech. It's about the obligations that come with the job. Free speech only exists in the context of role, and when it comes to some roles (Paisley's and my own professions included), some public comments can never be made in a private capacity.

None of us are entirely free in the sense that the free speech defenders think. Or rather, there's an easy solution if one finds the constraints on speech that one has volunteered to adopt too much. Resign.