ir/rational: Are You Human?

Alternate post title: Conumdra. For this is a short semi-text adventure from Tom Jubert, who’s best known for writing the Penumbra series of heavily bephysicsed action-puzzlers. Apparently ir/rational began life as minigame for inclusion in one of the Penumbras, but now find itself standalone.

It is a free videogame.
Therefore you will play it.
It tests your logic and deductive reasoning.
Therefore you may be too lazy to play it.

But you should.

It won’t take long (though I got stuck for a long time on the last of its 10 puzzles, but that’s because I’m not a real human being), it’ll make you feel slightly clever, and it might make you question some of its logic. I know I felt a couple of solutions didn’t ring true. But then that’s probably part of the point.

I don’t wish to describe it in much detail because I fear that going into its mechanics might make it sound boring – instead, I’ll summarise that it concerns a stalemate between a (presumed) human and a sinister machine which holds him/her/it captive. You have to break that stalemate. Using only THE POWER OF YOUR MIND. Um, and your mouse.

Also: it’s well-written, funny, and takes an unexpected and vicious pop at an Austrialian politician. You’ll like it.


  1. GGX_Justice says:

    Utterly, utterly, brilliant.

    All that really needs to be said. Although the fact that I’m rapidly getting a man-crush for Tom Jubert can’t possibly hurt.

  2. Peter says:

    I’d like it more if the author understood that ((A->B) ^ B) -> A is NOT true, though it is true that ((A->B) ^ ~B) -> ~A. As it is, the expected answers to the Jack and Jill question, and to the final question, are so much nonsense. Oh well.

    • GGX_Justice says:

      @Peter: Something I find interesting is that, having done my discrete mathematics and logic course I clumsly went through the processes I’d been taught, finding some questions quite… odd.

      Yet my friend who has studied philosophy found it a breeze. Food for thought?

    • etho says:

      I’ve studied neither math or philosophy, and I found it not too difficult. The hardest part for me was holding all the symbols in my head on the last puzzle. The jack and jill answers made sense to me. She’d had her weetabix, so she couldn’t be sick, but clearly someone was, since no one had fetched the water.

    • MD says:

      etho: the problem is, we were told that if jack or jill are sick, nobody will fetch the water. but we were not told that jack or jill MUST be sick in order for the water not to be fetched. (sickness was a sufficient condition for the water not being fetched, but not a necessary one). so the fact that the water hadn’t been fetched tells us nothing about their health.

    • medwards says:

      If you can’t understand the implies logical operator then I don’t want to play your game based on logical operators because you don’t actually understand basic logic. I was pretty close to dling this and am now glad I did not. Also A-scales point that his writing style could take a page from Orwell’s english writing essay seemed pretty damning.

    • JuJuCam says:

      @MD: “if jack or jill are sick, nobody will fetch the water. but we were not told that jack or jill MUST be sick in order for the water not to be fetched.”

      In fact we are told that if neither jack and jill are sick, then nobody will fetch water.

      We are required to make an assumption that the necessary condition for water to be fetched is that one or the other of them is ill. And the rest of the logical chain follows through from there. ie jill is healthy therefore jack must be ill.

      The key is that jack and jill, as in the nursery rhyme, did in fact fetch the pail of water.

    • JuJuCam says:

      … or have I got it completely arse backwards? That’s how I remember rationalising the ultimate correct answer after having failed it on my first instinct.

    • Barton says:

      Spoilers, I guess?

      Not sure what the problem with the Jack and Jill question was.

      1. (A v B) -> C
      2. W -> not(B)
      3. C
      4. W
      5. |= not(B)
      6. |= A

    • Barton says:

      Further reading into the comments has revealed what was wrong. Should have checked my own logical assumptions!

    • DMJ says:

      I love logic. If I recall my carefree, drunken logic-based software engineering lectures correctly it allows me to make true statements like this:

      If today is Sunday, then I am the Queen of England.

      Unless, of course, today is Sunday. And assuming I’m not the Queen of England. Which, just for the record, I’m not. Honest.

    • BooleanBob says:

      Regarding this, did nobody else have a problem with question one? I didn’t understand where it was established that pressing the switch would turn on a or the light (aside from it being described as a lightswitch, but that’s just language, yeah?).

    • Supraliminal says:

      BooleanBob :
      You are in a dark room. There is nothing else visible than a swich. You might just assume it is a lightswich and therefore fiddling with it will put the lights on.

      If the room was build by the/a machine, though, it might not be a lightswich, but you wouldn’t think something like that in a dark room, where is nothing but a (light)switch, yet. You had just been born, propably/maybe.

      In any case you would still press the switch, even if it wasn’t a lightswich. There just isn’t anything else to do.

      So no one told you that it is a lightswich, but they assumed you would think of it yourself, eventually.

  3. pkt-zer0 says:

    Could be fun, if the drop-down boxes were consistently positioned correctly in at least one of the versions. Argh.

  4. Coded One says:

    Bah… stuck on number 9. Any help?

    • Coded One says:

      Nevermind, I just skipped it. Good ending, I like it.

    • Barton says:

      Consider the two assumptions that are given, and you should notice that something doesn’t add up.

  5. A-Scale says:

    I like the concept but I’m immediately struck by how hard the author is trying to sound creative and intelligent. It’s painful and actually makes me like the game less. He or she needs a lesson from Orwell.
    link to

  6. A-Scale says:

    Also, the jab at Descartes is bollocks. Knowing that you’re an existent, thinking being is the most fundamental and important piece of knowledge we have, and it tells us much about what the world is like.

    • TeeJay says:

      “Kierkegaard argues that the cogito already pre-supposes the existence of “I”, and therefore concluding with existence is logically trivial”

    • etho says:

      I’m with Kierkegaard on this one. Cogito Ergo Sum always struck me as silly.

    • Tom Jubert says:

      PS I have massive love for Descartes, but clearly the character does not.

  7. Joseph says:


    I don’t understand 10. It seems like he drew the conclusion that O is true in the third problem without adequate evidence. Correlation with the parameters to POSSIBLY be O, but not enough to make the leap that it was definitely O. it was clearly the answer that he wanted, but i’m pretty sure it was also clearly unsubstantiated with the logic he gave us.

    • Barton says:

      Extended spoilers?
      Yeah I noticed that too; Tom didn’t consider the potential vacuous truth. I had to go back and re-read the question because I thought I was missing something.

  8. Tacroy says:

    Yeah there is some false logic here – if A->B and B, you cannot say anything about A. For example:
    IF pelicans bring babies THEN there will be more pelicans where there are more babies. (a reasonable consequence – if more babies are being born in an area, there must be more pelicans to bring them)
    There are more pelicans where there are more babies (actually true in some cases)
    THEREFORE, pelicans bring babies (actually false).

    What is true is if A->B and not B, therefore not A. e.g:
    IF pelicans bring babies THEN there will be more pelicans where there are more babies.
    There are not more pelicans where there are more babies
    THEREFORE, pelicans do not bring babies

    I had more trouble with the last question than I should have because I kept on looking at it and going “uhh I can’t say anything about that”. Oddly enough I didn’t have much trouble with the Jack and Jill question – it was probably the trappings of predicate calculus that brought back all of the rules.

    • Joseph says:

      I didnt see the same contradiction in the jack and jill one, because he specified that if EITHER jack or jill was ill, they wouldnt get water. No need to question why that was in context, it made the solution accurate under those parameters.

    • Joseph says:

      nevermind, same problem in the jack or jill question, i just overlooked it as i breezed through the ‘easy’ ones. There’s no way to say something else hasnt prevented the water being fetched, to assume jack is ill is tenuous at best.

    • etho says:

      I think the point was to make logical conclusions based solely on the information at hand. there is no indication that anything else other than illness could prevent them from fetching water, so if they didn’t get the water, based on what we know, one or both of them had to be sick.

    • Peter says:

      Well, the thing about the Jack and Jill question is that the correct answer is available (Jill is not ill AND Jill is not ill) but when you put that in, it calls your response “false.” First, that’s just true by tautology, so it’s not false, and second, it’s the best you can do under the circumstances. Any other conclusion he offers, say that Jack is ill, is specious.

  9. Empyreal says:

    A-Scale: I actually quite liked his writing style. It reminded me of Hitchhiker’s Guide to the Galaxy. It’s not like that’s the only book I’ve read either, I’m a big book person, so it’s not like I only know one style and a not book-savvy enough to understand different styles or compare them, but I thought the writing style was charming nonetheless. However, tastes differ, but I thought that it was appropriately written for the style of game.

    • A-Scale says:


      It was just too flowery. It broke the flow by adding in too many adjectives where there should have been none. It’s the sign of someone trying to make up what they lack in storytelling with verbiage.

    • BooleanBob says:

      Hmm. I think you’re being a little harsh. In my opinion, it’s actually fairly well written. Perhaps you’re transferring the ‘excessive verbiage’ of the character to the author. He’s meant to be reasonably wordy, that is, of ‘lengthy vocabulary’. His tendency to slip redundant and awkward adverbs into sentences (interestingly) does a decent job of conveying a slight arrogance and overconfidence – a disposition from which he can convincingly make a whole bunch of assumptions, such as ‘IF I can outwit this computer, THEN a way out of this room will appear, IF a way out of this room will appear, THEN I can escape’.

      Feeding both the philosophy and the joke experientially through a character, and thus through a specific idiolect, gives him an opportunity do things with the writing that play with the concepts and stretch them in a few interesting ways that would be beyond stylistically sanitised (by the Orwellian method or any other) textbook treatise or straight-faced quiz.

      I reckon.

  10. A-Scale says:

    I agree with the last two commentators- #3 on part 10 was incorrect.

    Decent game overall. Good way to study up for the law exams while having a bit of fun. The direct Portal feel was a bit overwrought though.

  11. MD says:

    Easier than the author’s mum, and just as shallow.

  12. BootS On Sale says:

    While you may feel that finding a Cheap Ugg Boots is an impossible quest, let me assure you that it is possible.With a little luck, a willingness to spend long hours online and in discount stores, you can find a Cheap Uggs boots.
    With the coming of Christmas Day,Owing a pair of Ugg Classic Short Boots is now doubt that increasing the festivals atmosphere.

  13. Bret says:

    I doubt that boots is human.

  14. Santiago says:

    I would have liked it better if winning the game required you to be irrational. Where´s the message, the metaphor? Though the guy was so nice I feel bad for criticizing him. Oh! the humanity!

    • MD says:

      It did, though!At least one of the ‘correct’ answers was flawed, and apparently two. (Not ‘apparently’ because I doubt the people who have pointed it out, I just didn’t notice it myself.)

    • MD says:

      Ah there it is, replaying now and yeah, question 5 treats an IF as an IFF (if and only if)

  15. Vinraith says:

    Math background here, but I haven’t had a discrete course or problem in about a decade. I found it quite easy, though I failed to note the logical error in part 5. I did notice the logical fallacy in part 3 of question 10, but there was only one answer that the author could reasonably have had in mind so it wasn’t a problem to select the correct incorrect answer.

  16. cjlr says:

    Aaaand now the site’s over its bandwidth limit.

    I blame you, RPS.

  17. wtfIDontGetIt says:

    wtf, level 4 makes no sense whatsoever… ANY help would be thoroughly appreciated!

    • bill says:

      IF (hint button exists) AND (user needs a hint, any kind of hint) THEN _____________________

  18. Tacroy says:

    eth0: logically, you can form no concrete conclusions about Jack in the Jack and Jill question. Yes, you are given some information, and one potentially true world-state is that Jack is sick; however, there are a literally infinite number of true world-states in which water has not been fetched and Jack is not sick. For instance, Jack may have broken his leg, which is not sickness but which would keep him from fetching water; the well may be empty, the bucket may be broken, Jack and Jill may have both died of any number of causes, or spontaneously turned into aliens who have no need of our hyooman water. You are given information, but it is irrational to assume that from the incomplete information you are given you can entail truth-values.

    You can certainly entail probability values, given a-priori knowledge of the prior probabilities of various world-states. In that case, yes, you could say that there’s a 70% chance Jack is sick; however, making such a determination requires information that is not present in the question as stated.

    I think it’s kind of funny, actually – the author in the very beginning states that:

    “… you might find that sometimes the answer you think is right… isn’t. That’s because we human beings are clever, and we make leaps of logic that we don’t always notice”.

    I’m not sure if it’s ironic or not, because I’ve completely lost track of what that word means.

    • Supraliminal says:

      Tacroy :
      You do understand that the “thing” of these kind of logic problems is that you don’t make up any values of your own.

      If the probability of jack breaking his leg is not listed in the facts, it’s not to be taken in the conclusion.

      -If Jack or Jill is ill THEN no one will fetch the water.

      That is the only variable regarding the fetching of the water

      Facts say that:
      -Jill is not ill
      -Water hasn’t been fetched.
      There is only one “logical” outcome.

      It isn’t real-world-logic, not even close. It’s the kind of logic philosophers used to practise in the old days and what modern virtual text puzzles are benefiting in order to look clever.
      And they are doing well, in that matter.

    • Mark O'Brien says:


      I’m sorry, but you are almost certainly wrong (and the creator agrees there are problems with this puzzle).

      The “kind of logic” that philosopher’s use, as you put it, is quite clear that you cannot use a statement “IF A THEN B” along with a knowledge that “B” is true to prove that A is true.

      It doesn’t matter that Jack breaking his leg is not in the puzzle. What IS in the puzzle is not sufficient to prove that Jack is sick, because it does not state that Jack will definitely fetch the water if he is not sick. This is because the puzzle does not state “If Jack is not ill or Jill is not ill, they will fetch the water”, it says “If Jack is ill or Jill is ill they will not fetch the water”.

      As much as it may look like it, these statements are not equivalent.

      It’s the difference between these two sentences.

      If it rains, I will wear a coat when I go outside. (This is more or less true)

      If it is not raining, I will not wear a coat when I go outside. (This is more or less false; I may wear a coat because it is cold)

    • archonsod says:

      You’re trapped in a small room and potentially have just been born. I figure the point of that was to suggest that your knowledge of the outside world was nil, and force you to use only the information you’d been fed.

    • Mark O'Brien says:


      You are not required to have real world knowledge to know there’s a problem with the logic. Saying that Jack may have broken his leg is just an example to prove the point.

      If you really had no memory and no outside world knowledge, you would just have to wonder whether it was possible that any other reason could have prevented Jack from fetching the water.

      This is perhaps more obvious in question 10, where real world knowledge doesn’t come into it at all because it’s all just symbols. Even though there is no real world knowledge to draw on, the question is clearly incorrect based on the well known rules of working with propositional logic.

    • Supraliminal says:

      Mark O’Brien:

      Ehh, I’m not the right guy for splitting hairs about the irrational logic of a logic puzzle.

      It just doesn’t matter in the slightest.

      I’m quite sure (nearly) everyone got through that particular Jack and Jill dilemma, not getting stuck in the matter of possibilities of what could have happened to the kids in the happyland they quite possibly, though not stated in the text, lived, while they were, or were not , trying to fetch some water for their granny, who obviously wasn’t there originally. Or was she?

    • Supraliminal says:

      And the question 10 makes perfect sense, for me at least…

    • Mark O'Brien says:


      Again, it’s not really a question of it being easy or hard. For me, it’s as if the puzzle asks you to “add 12+12”, and gives you the options “25”, “232”, “2342”, and “zebra”.

      It’s not hard to pick the best solution of a bad lot (“25”) and therefore get the puzzle right, but it leads to a feeling of dissatisfaction with the game, or at least a few minutes worrying if you’re missing something.

      I blazed through the Jack and Jill question without really noticing it was wrong. Question 10 is where I could very obviously see there was a problem (because I had some training in logical operations in college), so I wasted a few minutes in puzzled confusion over what I was missing, despite seeing that of the available options for the last dropdown only “O” made any sense.

      This is particularly as I was led to believe that the game would be challenging you to resist your human intuition (which can occasionally lead you astray) and to instead think very carefully and precisely like a machine (which, within very constrained parameters, will lead to an irrefutably correct answer). This is arguably the difference between irrationality and rationality as indicated by the title.

      Jack and Jill seems right because the conclusion relies on intuition. I would be more impressed by the game if it exploited the discrepency between intuition and logic a little bit better by giving options which seemed correct but actually weren’t, while the correct answers were actually very unintuitive.

  19. Ronnie76er says:

    Destroyed already…

    Any mirrors out there?

  20. pepper says:

    Your’e actually seeing that wrong, he understands the operators, but just enjoys confusing the hell out of us by overloading them and not documenting it! He just wants to poke fun with the math and programmers that play it.

  21. Kast says:

    The Game; you broke it.

  22. zaekrex says:

    Omg we need a mirror, I want to try this out… :(

  23. Aemony says:

    Nooo! The bandwith was just exceeded! A MIRROR, I’D GIVE MY COUNTRY FOR MY MIRROR!

  24. Ian says:

    RPS done broked the game!

  25. Brer says:

    Affirming the consequent is one of those incredibly pernicious logical fallacies that seems to creep back into the logic of even the most rational people if they allow themselves to get careless (as the designer here obviously did).

  26. deadacc30203 says:

    If sequels are forthcoming, I would recommend submitting the final beta version to someone with graduate-level qualifications in a logic-based field. For a start, get a course listing from a local college and find whoever’s been saddled with teaching the “Intro to Symbolic Logic” or equivalent class. I am certain, for example, that the gentleman who taught my undergrad-level classes would have LOVED to have pointed his students at a product like this, was the logic within it truly valid. I’d tell you to submit it to someone on the comp-sci or pure math side of the divide, but not all of those folk are highly skilled at parsing the vagaries of the English language, however skilled they are at resolving the math behind the philosophy.

    All of that said, I think that sequels thus vetted would be a really good thing.

  27. Psychopomp says:

    @ everyone complaining about the games lack of logic

    link to

  28. deadacc30203 says:

    @ Psychopomp

    Rationally speaking, there’s evidence against that assertion. The author’s notes make a point of saying that the problems in the program were “real propositional calculus” and that “no corners had been cut” in the process of hiding the symbolic logic underlying the English-language problems within. Yes, there’s some meta-humor in an attempt at a logic game failing to be logical, which possibly borders on true irony, but the evidence available suggests that entirely outside of the fictional Machine’s own logical failures, rewarding faulty thinking on the part of the player was NOT the author’s intent.

  29. Blandford says:

    I’ve been stuck on level 9 for the past… 30 minutes now?
    Call me stupid, I need help.

    • sabbyp says:

      going from the machine’s answers to the protagonist:

      the machine thinks smugness is a relevant clue
      the machine thinks smugness is a red herring

      (regardless of the fast it knows not what a red herring is, *that’s* the red herring!)

      if the machine thinks BOTH of these things then it’s contradicting itself!

    • sabbyp says:

      meant to say *fact there

    • Hmm-Hmm. says:

      See, that’s my beef with this game. I know this and still can’t get past this. I have the feeling it’s not so much to do with the fact that I can’t see everything because of the menus but more the specific way you’re supposed to phrase the arguments.

  30. Duke says:

    So… did anyone send the man a friendly letter informing him of this error since he requests feedback at the end of the game?

  31. BigJonno says:

    I have no experience with this kind of thing, but managed to get through once I’d got in the right frame of mind, as it were. I fudged the last puzzle after reading this thread (I had the first two parts right, I just couldn’t get the last one) although I take comfort from the people on here saying that there’s an error.

    Interestingly enough, I found the Jack and Jill puzzle to be one of the easiest. I don’t know if it’s because that’s when I’d hit my stride, or if it was because it took more effort for me to think logically, but it was obvious that there weren’t any other factors to be considered because they weren’t included in the puzzle.

  32. Sinnerman says:

    I like it despite not being able to read some of the text with either version, but had the most problems with 4 for some reason. I felt that it was sometimes a test of trying to put things in the right order and in at least one question it didn’t seem to accept what I though was a valid proof by contradiction. The last question was by far the easiest for me.

  33. megaman says:

    Using wine I have a hard time reading the texts because they are overlayed by dropdowns – in both the standard and dropdownfix executables. Using both, I was able to deduct most of it but in level 9 I’ve hit a border I can’t cross since there’s not enough left to read.
    Why, oh why, is so simple stuff not just done in old-school html? Or at least as flash? And would someone be so kind as to tell me what is written in level 9?

  34. Mark O'Brien says:


    It’s not about whether it was easy or hard. Those of us who think there was a problem with those puzzles didn’t necessarily find them difficult. We just thought that they were basically flawed, especially in a game which takes as its premise a test of your rationality, as opposed to making intuitive leaps based on assumptions.

    If you say Jack is ill, then you are definitely assuming that nothing else could prevent them fetching water instead. That doesn’t fit within the logic of the game. It might be fine in a regular adventure game or something, but not in a game that appears to be trying to test rigorous logic.

    • BigJonno says:


      Couldn’t you apply the same criticism to any of the other problems? The oxygen one makes the assumption that you are human. Within the context of the game, it’s possible that you could be an alien life form that doesn’t require oxygen, in which case you could be alive without requiring oxygen or the laws of human biology being broken.

      It’s safe to assume that if the water hasn’t been collected then it’s because either Jack or Jill are ill, because the game gives you no other information to work with. It’s easy to say that the Jack and Jill problem is flawed, because it’s easy for us to think of additional reasons for the water not to be fetched.

  35. Tom Jubert says:

    LOL, thanks for breaking my site guys! (And I mean that in the nicest possible way). Emergency cheap-arse mirror here: link to

    More than anything, I’m pleased the game is prompting some passionate-ish debate, and that at least some people enjoyed the writing. It is fairly verbose, but that is intentional, and I hope any time you spend with future iterations of this, or the Penumbra series, will be more palatable for those that didn’t enjoy the unnecessary adjectives.

    Not that I need to confirm it, but there are some logical inconsistancies in here. Would love to claim they were all a part of the grand metaphor, but I’m afraid that’s reading too much into things. In honesty – yes, there are school-boy infirngements of affirming the consequent. I left these in there not because I’m an idiot, but because I figured only people who know anything about logic would notice them, and that for everyone else being quite so logically pious would only confuse things.

    Clearly I underestimated how many gamers have studied logic! I hope I’ll have the opportunity to work on a more polished iteration some point in the future.

    And yeah, that menu positioning bug. Shit. That thing just never goes away. I’ll see if I can get out a smoother version.

    Take it easy


    • Mark O'Brien says:

      @Tom Jubert

      I’ve been on this thread a lot explaining why there is a problem with these puzzles and also why I think it matters that there is a problem with the puzzles.

      Probably part of the motivation for why I’m posting so much (I’m normally a lurker) is that I actually really liked the overall concept and enjoyed the other 8 puzzles, which is probably why I care.

      Just don’t want to seem like I’m negative about the overall experience.

      Good job overall!

    • Tom Jubert says:

      Thanks Mark :-) I know how easy it is to get dragged into an argument when someone’s being *aha* irrational.

      I’ve just put up a new version which may make the purists a little (if not entirely) happier.

  36. Tom Jubert says:

    PS General apologies for my rubbish programming – believe it or not I’m a writer by trade. Naturally it’d be a dream to produce a version or sequel in collaboration with a decent Java / Flash programmer, that way I could focus on not fucking up the logic for you :-)

    Any volunteers, you’ve got my number.

    • Mark O'Brien says:

      I might be interested. I’m a professional Java web app programmer, and I’ve done a little bit with Flex (Flash based web app thing).

      Possibly don’t have enough time on my hands though. It would depend on what exactly you were planning and how interesting it seemed as a project.

      One suggestion: it might be interesting to acknowledge incorrect responses with a bit more than “false”. For instance, as I and others have noted, it is possible to enter logically consistent statements that don’t make sense, or were not the answer you were looking for.

    • Tom Jubert says:

      Agreed. I actually had specific feedback in an early build, but naturally it’s a lot of work to add in five or more different fail screens for each puzzle.

      I have ideas for where the game could be taken on a commercial level. If you fancy a chat, you have my email :-)

  37. Blandford says:

    So I had the answer all along, I just didn’t think i was supposed to use “The Machine has contradicted itself” in part 4. Just seemed silly.

    Thanks for the help.

    • sabbyp says:

      silly maybe, but logical :P

    • Hmm-Hmm. says:

      I had more trouble with seeing the game through the menus and the specific way you have to phrase your answers than with the logic itself. The fourth and the ninth ones were annoying, but others were much less so. Annoying because you know what it should convey but apparently you have to anwer it in his way.

  38. Igor Hardy says:

    Great attempt at making logic seem boring. Otherwise lousy game. Thankfully it is short.

  39. 9of9 says:

    I agree, it’s an interesting concept as a game – doing propositional calculus can be quite fun – but while the writing might be decent, the logic coud use a bit more work. The Jack and Jill one isn’t so bad I suppose, since you can claim to rely on the hidden assumption that if neither of them are sick, then the water is fetched. Of course, no reason not to offer that assumption explicitly in the argument.

    The last one frustrated me more because you there’s no hidden assumption to be found – the author forces you to commit to a fallacy. Considering logic is the whole point of the game, that really defeats the purpose.

    Also, in a few places like the herring puzzle it seems to be rather particular about the order in which you put the propositions – making you fail on on valid arguments. And in spite of all this, it’s entirely too easy.

    Good concept, but not a very impressive execution. Perhaps he should get a logician to design the puzzles for him and stick to the writing. Maybe a programmer too, since I really don’t understand how you can mess up drop-down menus that bad.

  40. Mark O'Brien says:


    Interesting point, but I think it’s a different kind of assumption.

    From the point of view of sheer symbolic logic, the oxygen question takes the form

    A => [B] v [C] (if A then B is true or C is not true)
    [A] ^ ¬C (A and C are true)
    Therefore B is true

    Options from which you choose are indicated by square brackets.

    A means “I am alive”
    B means “I am breathing oxygen”
    C means “The laws of human biology have not been broken”

    So, your objective is to fill in values so that IF your assumptions hold, then B is true.

    I suppose you are free to choose your assumptions. If you chose instead…

    “If I am alive, then I am breathing oxygen or I can drink water”
    “I can drink water and the laws of human biology have not been broken”
    “I am breathing oxygen”

    .. then you would have something which made logical sense even though it’s gibberish from a real-world standpoint because the basic premises are false. The correct answer is the only one which makes sense from both a real world point of view and that is provably true from the point of view of mathematical logic.

    You correctly state that it assumes you are human, but from the game’s point of view that’s reasonable because there is no option to state this or to suppose that you are not human.

    The case with Jack and Jill is different because the “correct” answer makes sense from a real-world point of view but it doesn’t hold mathematically. This means there are sensible real world cases where every assumption in the puzzle is true, but the conclusion is nevertheless false, e.g. there is no water at the top of the hill, or Jack doesn’t like going to fetch water alone. I don’t think this can really be said about the oxygen question. If you are not human, then the assumptions don’t hold true, so the conclusion is irrelevant.

    • Mark O'Brien says:


      I still don’t get how replying works.

      Anyway, I made a mistake in my example of correct logic with nonsense real world.

      I meant to say

      “If I am alive, then I am breathing oxygen or I can drink water”
      “I cannot drink water and the laws of human biology have not been broken”
      “I am breathing oxygen”

      Umm, actually there’s a problem with that too, because you have to state the assumption that you are alive for it to work.

      A better example would be

      “If I am alive, then I am not alive or I can breathe oxygen”
      “I am alive and the laws of human biology have not been broken”
      “I am breathing oxygen”

      Again, it’s gibberish from a real world point of view but it makes sense mathematically.

  41. Sergey Galyonkin says:

    Half and hour? Well, if you’re just out of kindergarten – maybe :)

    Completed it under 10 minutes. Very good, I’d like to see more like this.

  42. WidowFactory says:

    Well that was dull. Great for the pretentious, not so much for people who look for games for entertainment.

    • Mark O'Brien says:


      It’s probably arrogant to assume that anyone who enjoys something you do not is pretentious.

      I generally associate pretentiousness with “arty farty” stuff anyway, not with mathematics/logic. Maybe it would be fairer to say “great for the nerdy”?

      Even then, while I don’t generally appreciate things which are overly artistic or abstract (David Lynch films, for example), I wouldn’t jump to calling them pretentious necessarily. Perhaps they are great but just not for me, or perhaps I just don’t get them.

  43. disperse says:

    Humorous typo on the website:

    “forumulate logical proofs to progress through the game”

    Does that mean the author secretly expects us to get all our answers from the forum?

  44. abecedarian says:

    “Bandwidth limit exceeded

    We are sorry, but this site has exceeded its bandwidth limit at this time. Please try again later. For more information, see Google Sites help.”

    Well, that wasn’t very fun at all.

  45. OJ287 says:



    Think laterally… Don’t give up – it took me a while to work it out at first too.

  46. Tom Jubert says:


    Hint: mirror…

    link to

  47. Fazer says:

    Ouch, bandwidth limit has been exceeded on his page.

  48. Davee says:

    Argh! The horror, the horror of bandwidth limitations! Why must they exits when such pain is aflicted upon us poor internet-users?!

  49. Matt W says:

    I suspect the underlying problem is just that if you actually, faithfully stick to proper propositional logic you’re likely to significantly restrict your audience. The conditional-antecedent rule, for example, while the best formalization of a fairly sloppy English-language convention, is often confusing as all hell to non-logicians.

    On the other side of the coin, any logician who can’t reason out the required solutions to the problems presented here (with a modicum of trial-and-error in a few cases) should go back to their PhD and stop trying to interact with the real world :P

    (Doesn’t entirely excuse the game claiming to cut no corners, but otherwise it’s probably the right decision IMO.)

    Also, those of us trying to play on a netbook with a 600px screen height aren’t well-served by the vertical height of the app. Some scaling in the sequel would be nice! :)

    • Mark O'Brien says:

      @Matt W

      I don’t see how it’s the right decision to have faulty logic in the game given that it would be so easy to fix it.

      There’s no reason the two faulty problems couldn’t be adjusted ever so slightly both to be logically consistent and also keep the non-logicians happy.

    • Joseph says:

      Yeah, agreed. Change jack and jill to ‘if either is ill’ and flip the order of question 3 — ‘if not e or not r then o and v’ and your logic all works. It’s almost as if he never proof read this game, or truly had absolutely no understanding of the subject and was just copying and rephrasing shit off the internet.

    • Matt W says:

      @ Mark & Joseph I’m not sure that’s something one can judge properly without doing some playtesting or similar to figure out exactly what would or wouldn’t trip people up. It is possible that it’s just the designer not thinking things through, but I’d allow that it’s also possible that it’s the designer making a judgement call on readability vs precision.

      (I’ve been in a fair few small-group classes on logic with people who didn’t come into it with the right mental tools to handle it. I always found it hard to understand exactly how someone could have so much trouble with something I find so straightforward, but it made me appreciate how difficult it can be for some. On the flip side, I can’t draw for shit, so I guess it all balances out.)

      On the assumption that the game is supposed to act as an introduction to logic rather than a challenge for those already in the know, on the evidence of this thread it’s worked out alright. I can see two sorts of discussions about the Jack and Jill problem: one group arguing about the construction of the problem which they’ve already beaten (presumably logicians) and one group asking what the fuss is as they found the question easy (presumably non-logicians). If the latter group are the target audience and they’re getting through fine, then there’s no immediate problem – and I don’t see this game as being nearly comprehensive enough to be instilling bad habits.

    • Mark O'Brien says:

      @Matt W

      I can see where you are coming from and it’s a reasonable point of view. Personally, I don’t see any reason to believe that fixing these puzzles (particularly 10, which is just cryptic logical symbols anyway) would lead to a decrease in readability, while it would be a lot less confusing for those with a bit of knowledge about the rules for manipulating logic.

      I do find it a bit annoying that a game that has as its purpose the introduction of logical principles to novices would make a basic mistake like this. If you’re going to teach, I think you have a responsibility to teach correctly!

      In fairness to Tom I think it was just a mistake and these things happen. I’m just voicing disagreement with those who think it’s fine the way it is.

    • Matt W says:

      @ Mark well, I’d be lying if I said I didn’t think “hah, that’s inaccurate in proper prop logic” while I was doing it :)

  50. Berzee says:

    Ehh, the ending retroactively ruined it for me. Dunno why so many indie games go that route o_-