Directions:

In Hitchcock's wickedly twisted tale of voyeurism, murder and critical reasoning, Jefferies (the injured photographer), Lisa (his high society girlfriend), Stella (his day-nurse), and Lieutenant Doyle (his friend on the police force) try to solve the mystery of what really happened to Mrs. Thorwald. Along the way, each of these sleuths has ample opportunity to exercise reasoning skills--sound and fallacious. Below are some of the major lines of reasoning highlighted in the film. Some are (at least partially) valid; some are utterly mired in fallacy. You must label the specific form of reasoning, or the specific fallacy in each of the instances below. ALSO, when you diagnose an instance of reasoning as fallacious, you need to explain exactly how it commits the particular fallacy that you identify.

1. All men are miserable after they get married. Their wives nag them and force them to give up most of the things they enjoy. Therefore, I can conclude that if I do wind up marrying Lisa, I will wind up miserable and be forced to give up most of the things that I enjoy.

2. Let's see here. In the building across the courtyard, the salesman and his wife are always fighting and unhappy. Also in that building, the newly-wed couple who just moved in seem destined for unhappiness since the bride is constantly summoning the groom every time he tries to enjoy a cigarette on his balcony. Looking at these two couples, I think that it is likely--or at any rate possible--that my marriage to Lisa will bring a similar unhappiness upon me.

3. Of course it's ordinarily wrong to peep at people's private behavior in their homes. In fact, there's even a law against this. But what if I can prove that a man is guilty or innocent of murder by my peeping through my neighbors' windows? Maybe there's a separate ethics of rear window voyeurism for such cases. And, after all, my neighbors do have the same opportunity to peep through my window if they so choose. So maybe it's OK for me to peep in on them in this case.

4. If Mr. Thorwald really did put his wife on a train to get their new home in the country ready for them, then she would certainly have taken her wedding ring with her. But her wedding ring is still here, stuffed in her favorite handbag, which is itself hidden in her husband's dresser drawer. Therefore Mr. Thorwald could not have put his wife on that train as he claims.

5. After Lieutenant Doyle explains how all of the evidence of murder is wildly inconclusive, Lisa hints that she just has a certain feeling of certainty--a feeling of so-called "women's intuition"--which convinces her and Jefferies that Thorwald is guilty. And since Lisa is a woman, and therefore gifted with a woman's intuition, Lieutenant Doyle should just forget all about his police training and trust in her hunch.

6. Everything seems to add up to the fact that Mr. Thorwald murdered his wife. First, there's the fact that he made several trips out into the rain in the middle of the night with his samples case. Second, his wife seems to have vanished sometime during that rainy night. Third, Mr. Thorwald spent the next day wrapping a saw and a couple of knives up in newspaper, and then scrubbing down the walls of his bathroom. The facts pretty much speak for themselves in this case. He killed her, cut her up, and moved the body-pieces in his samples case.

7. Listen Doyle, let's review your reasoning here. You say that Mrs. Thorwald's postcard announcing her safe arrival in the country establishes her presence there and discredits our hypothesis that she has actually been murdered. But you also note that Thorwald has apparently been in constant telephone contact with his wife since she first arrived in the country. This constant telephoning means that there was actually no need for Mrs. Thorwald to send a postcard announcing her safe arrival. And yet such a postcard has in fact arrived by mail.

8. If something were recently buried out in the flower bed, then the flowers are likely to have the appearance of having been re-planted. As these slides which I have been taking all week show, the flowers do in fact have the appearance of having been re-planted. Therefore we can conclude that it is likely, or at any rate possible that something, perhaps Mrs. Thorwald's remains, has been buried out in the flower bed.

9. If the dog were threatening to dig up Mrs. Thorwald's remains, then it should surprise no one if the dog should turn up dead. After all, anyone capable of killing a human being is certainly capable of killing a dog in order to hide his crime. Lo and behold! the dog does indeed turn up dead--right beside the flower bed where it had been digging.
Therefore we can conclude with certainty that the dog was killed because it was about to dig up Mrs. Thorwald's remains.

10. The dog must have been killed by one of the neighbors. It had to have been either the composer, the sculptor, "Miss Torso, "Miss Lonelyhearts, the newlyweds, or Mr. Thorwald. The dog was almost certainly not killed by the composer, the sculptor, "Miss Torso, "Miss Lonelyhearts, or the newlyweds because they all came out onto their balconies to console the dog's anguished owners. Therefore the dog was almost certainly killed by Mr. Thorwald, since he was the only one who didn't step out onto his balcony when the dog's death was discovered.