Wednesday, March 21, 2012


When I was in high school I remember finding in a book a way to make a crude syllogism computer using just index cards, a hole punch, scissors and pins (or sticks). There were holes punched in the cards, some of which were closed (i.e., circles) and others of which were open (i.e., the holes were like a little U-shaped bite into the card). There was a master card with a key to all the holes, and you'd stack the cards together, put pins in the holes that represented the propositions, and shake the stack a bit. Some of the cards would fall out and -- if I remember correctly -- those cards had the syllogisms that were valid with those propositions. I made it and thought it was the greatest thing for a while. I have no clue where I found this, but I've wanted since to find the instructions for it. Has anyone come across this themselves, or knows in what book it is found?


  1. Arsen Darnay4:23 PM

    Can't give you a pointer, but I used such cards, punches, and rods in research when I first worked at Midwest Research Institute circa 1971. The kits were available with blank fields. We made databases on these indexing articles, page-numbered book references, etc. and supplying index terms for each "entry," one card was one entry. Then, once the research was done, references could be extracted using rods through appropriate keyword holes. But we "lifted" the search results out. Such kits may still be available somehwere. E-bay?

  2. branemrys4:42 PM

    Interesting; you're right that the index-card syllogism computer was a variation on exactly that system, and it would actually make sense if it were an adaptation of a more general system in use. It's entirely possible that the valid syllogisms were lifted out rather than allowed to fall out -- it's been so long I don't remember all the details clearly. I'll look around and see if I can find any of these database card kits.

  3. branemrys5:16 PM

    No luck yet, but I've found a description for a version for indexing and sorting using Boolean algebra.

    And I've discovered some of the names for the general kind of indexing system: Needle Cards, or Knitting Needle Computers, or Edge-Notched Cards, or McBee Cards.

    Here is a much more complicated version for research classification.

    Actually, there seems a lot of information on the general sort of system, but it seems very scattered and it seems that there are lots of different names. But I still don't have a syllogism computer yet. (I could probably gin one up, of course, but I'd like to have it spoonfed to me.)

  4. branemrys5:28 PM

    It looks like Etsy (which is more craft-oriented than E-bay) is the place to go, e.g.:

    Vintage InDecks Set

    McBee Punch

    These are way more sophisticated than needed for the relatively simple system of sorting out valid syllogisms, though, since there are only twenty-four of those, counting very generously.


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