right against self-incrimination not leverageable into right to not testify, how?

All Western legal/constitutional systems nowadays have a basic right against self-incrimination (e.g. the Fifth Amendment in the US).

Under this right, what would keep me, as a witness in a criminal case, from refusing to testify with the following argument?

I will not answer your question because the answer would incriminate me of a criminal offence. I will not specify the offence or the way the answer would incriminate me because doing so would incriminate me, in a way that will not specify because doing so would incriminate me, in a way that will not specify … (ad infinitum)

In the US you can do that. In fact many years ago as a witness in a criminal case I actually did refuse to answer a question citing the Fifth Amendment.

How do you think the Fifth Amendment right works? You don’t even have to say as much as you did.

er… wouldn’t that mean that in effect everyone can refuse to testify about anything at all (in a case against a third party), whether it would in fact incriminate him or not? There are usually other, specific rights to deny testimony, depending on the legal system, e.g. professionally privileged information, right to not testify against one’s spouse, etc. - why would there be a need for those if a witness can refuse to testify anyway using the argument in the OP?

Nothing, except being charged with contempt of court.

Judges and lawyers aren’t idiots and don’t enjoy having the courts time wasted by fifth grade defense arguments. If they have a resonible expectation that you having information relevent to the case and there is not an application of the Fifth Amendment, a judge may in fact charge you with contempt or possibly purgury:

http://www.law.emory.edu/1circuit/nov95/94-2302.01a.html

http://www.showme.net/~capegadm/pa/INETDOMESTICVIO%20TAKING%205TH.htm

http://www.usdoj.gov/osg/briefs/1987/sg870369.txt

http://lw.bna.com/lw/19990511/88198.htm

And courts can also grant immunity so that your testimony can’t later be used against you in a separate prosecution.

No, because it only counts if you’d incriminate yourself. You can’t say, “I plead the 5th” if say, you want to save your best friend from going to prison because he committed murder. YOU aren’t involved in any sort of way, so you wouldn’t be incriminating yourself by testifying.

And often, the prosecution will work out a deal, granting immunity completely, or working out a plea bargain, in exchange for testimony. The 5th amendment isn’t a “get out of jail free” card-it has its limits.