Supporting an inference with logical reasoning and evidence

0:00- [Instructor] Hello readers. Let's play detective, shall we? My mama always told me not to jump to conclusions, but that's essentially what the skill of inference is. It's not really a guess. It's combining what you already know with what's in front of you and drawing conclusions from there.

0:16It's filling in the gaps. So look, I can look at this shape with gaps in it, and based on what the shape suggest and based on what I already know, I can say I'm pretty sure that's an elephant. When I do that, I'm making an inference. That's what we're gonna talk about in this video.

0:33Not just making an inference, but going back and supporting that inference with evidence. This is an essential skill. Knowing how to read between the lines can help you make sense of what's missing in a text, of what's being left unsaid, or maybe even to figure out if someone is lying.

0:51Let me set up an example, a little locked room mystery. There was a mouse hole in the wall of a kitchen. There is a heavy glass jar full of lovingly baked cookies with a heavy glass lid still on the jar. An hour ago, there were a dozen cookies in there, and now there are only six.

1:10From the jar across the floor to the mouse hole in the wall, there is a trail of cookie crumbs. The question readers is, therefore, who took the cookies? The answer is not a mouse. A mouse did not take the cookies. It's a things to set up. It's a frame job. How do I know that?

1:29The lid. Based on my background knowledge about mice, I don't think a mouse would've been able to lift and replace the heavy glass lid of the jar. Maybe if we knew a person had left the lid off the jar, the mouse would still be a suspect. But I can infer from the evidence I see and my background knowledge that someone else took six cookies and left it incriminating cookie crumb trail that led to the doorstep of an innocent mouse.

1:55And when I am defending this mouse in court, I will point to the lid as evidence in support of my inference. Let's do this again. But I'll give you a chunk of text to look at and then you'll get the chance to make your own inferences. Here is the first introduction of Agatha Christie's fictional detective Hercule Poirot.

2:16The narrator describes Poirot. Poirot was an extraordinary looking little man. He was hardly more than five feet, four inches, but carried himself with a great dignity. His head was exactly the shape of an egg, and he always perched it a little on one side. His mustache was very stiff and military.

2:34The neatness of his attire was almost incredible. I believe the speck of dust would've caused him more pain than a bullet wound. Yet, as a detective, his flare had been extraordinary, and he had achieved triumphs by unraveling some of the most baffling cases of the day.

2:50And for you, I have a question now, readers. Based on this description, what personality traits do you think Poirot has that make him good at solving mysteries? I'll put on some music, or you can take this time to pause the video and discuss. We'll meet back here and I'll show you how to answer this question by making some informed inferences.

3:12(upbeat music) Okay, let's go through it. So what traits does Poirot have that make him good at solving mysteries? I think the words I'd use to describe Poirot are fussy or detail-oriented. How do I know that? Let's go to the text. He carries himself with great dignity.

3:40He's proud of his appearance. He has this stiff little mustache. "The neatness of his attire was almost incredible." That is to say, literally incredible, unbelievable. His clothes were so neat, unbelievably so to the point where a speck of dust would hurt him like a bullet hurt someone.

3:59All those details lead me to conclude that he notices little things. You have to notice the little things if you're going to keep yourself so neat. So exquisitely tidy and free of dust, a spectacular attention to detail. I can infer that that's the personality trait that leads him to notice things other people wouldn't notice, and makes him such a great detective.

4:22As you read, it's important to keep checking for text evidence that supports or discredits your initial inferences. Sometimes they'll be wrong, sometimes right. But usually the rest of the text will help you determine that. Now, do I suspect that you or I or any of us are likely to become mystery solving sleuths?

4:42Well, yes, actually I do. I just think it'll be through the skill of inference in your reading practice and not through solving murders. Though from the evidence presented, I wouldn't rule out that possibility. You can learn anything, David, out.