Having just been annoyed (ok, ok, I'm an old grouch) for the $n$-th time by seeing a question mis-tagged (indeed, mis-titled) , I've just realized there is no appropriate tag for questions that concern predicate logic, predicate calculus, quantificational logic, first-order logic (whatever you want to call it).

So, hopefully to get the ball rolling, I've retagged the last couple . I think that's probably to be preferred to two of the other options ("calculus" is a bit old-school, "first-order logic" could be a bit restrictive). But maybe others would prefer "quantificational logic"? But we should surely encourage the use of one or the other and deprecate the use of "propositional-logic" for questions that essential concern the logic of quantifiers.

Edit [Jan. $27$th A.K.]:

Can we please make agree on some reasonable state, the current one is heading towards being very messy.

  1. The main tag, has over a thousand questions which makes sense to allow better fragmentation into specific parts.

  2. We added quite some time ago, and it has 171 questions at time of this edit. This was also fine, because it seemed useful.

  3. There are the barely used and , and of course . There are also the even scarcer tags, and .

  4. Recently there has been a and which seem to me has having a lot of overlap, at least with respect to this site, and it's probably wise to merge them.

  5. We also have , which always baffled me. And the which takes some of the propositional calculus questions.

It seems that a good cleanup is in order. First order.

  • $\begingroup$ Apologies if so -- though it's one of those questions of nomenclature which can exercise people! So a question addressed to fellow logicians more widely than the (very?) few who read the meta questions. $\endgroup$ Commented Jan 22, 2013 at 7:42
  • $\begingroup$ There exists quantifiers tag. Should it be synonym with the newly created predicate-logic? $\endgroup$ Commented Jan 22, 2013 at 8:21
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    $\begingroup$ @MartinSleziak The quantifiers tag has no explication at the moment. But (to me) a question about "quantifiers" suggests something narrower in some ways, wider in others, i.e. a concern with understanding quantifiers in formal or informal languages. The suggested tag predicate-logic primarily concerns derivations in quantification theory. $\endgroup$ Commented Jan 22, 2013 at 8:33
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    $\begingroup$ Would predicate-logic differ from first-order-logic in some major way? (They both appear to be quite new, so perhaps they should be merged.) $\endgroup$
    – user642796
    Commented Jan 22, 2013 at 14:20
  • $\begingroup$ That's odd: I missed "first-order-logic" when I looked recently. Or is it very new?? I wouldn't object to merger -- except that "predicate-logic" perhaps usefully covers more (i.e. second-order logics too). $\endgroup$ Commented Jan 22, 2013 at 14:33
  • $\begingroup$ As far as I can tell, first-order-logic was first used on the 5th version of this question on 13 Jan. $\endgroup$
    – user642796
    Commented Jan 22, 2013 at 14:38
  • $\begingroup$ Peter, I hijacked the thread instead of starting a near-duplicate. $\endgroup$
    – Asaf Karagila Mod
    Commented Jan 27, 2013 at 10:33
  • $\begingroup$ @AsafKaragila I very much agree with your sentiments $\endgroup$ Commented Jan 27, 2013 at 11:40
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    $\begingroup$ @Asaf: Here is an older question about boolean-algebra tag. $\endgroup$ Commented Jan 27, 2013 at 13:02

1 Answer 1


Yes, I like to search through logic questions to learn something new and I was lately surprised by lack of predicate calculus tag. I think this is so fundamental for logic that we should have this tag. According to Wikipedia those terms would be correct: predicate calculus, quantification theory.


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