Make simple deductions

Welcome to the World of Simple Deductions!

Have you ever looked at a set of facts and realized that something else must also be true, even though it wasn't explicitly written down? If so, you’ve already started making deductions! In the Thinking Skills (9694) syllabus, making simple deductions is a core skill within the "Understanding and using information" section. It is all about finding the "hidden" information that is already contained within the data you are given.

Don't worry if logic puzzles sometimes feel a bit confusing. We are going to break this down into easy steps so you can tackle any problem in Paper 1 or Paper 3 with confidence.

What Exactly is a Deduction?

A deduction is a conclusion you reach based on evidence and reasoning. In this subject, a deduction is only valid if it must be true based on the information provided. If it "might" be true or is just "likely" to be true, it is an inference or a guess, but it isn't a solid deduction.

The Golden Rule: If the facts provided are true, the deduction cannot be false.

A Simple Example:

Fact 1: All students in the classroom are wearing blue shirts.
Fact 2: Sam is a student in the classroom.
Deduction: Sam is wearing a blue shirt.

Notice that we weren't told Sam’s shirt color directly, but because of the facts, there is no other possibility. This is a simple deduction.

How to Make Simple Deductions

In your exam, you will usually be given a short paragraph of text, a table, or a simple list of rules. To extract a deduction, follow these three steps:

1. Identify the Relevant Facts

Filter out the "fluff." Look for specific constraints, such as "never," "always," "more than," or "only." These words are the keys to unlocking the answer. (For more on sorting data, see the chapter on Identifying and selecting relevant information).

2. Look for the "Bridge"

Deductions usually happen when two pieces of information share a common link.
Example:
Fact A: \( \text{Apples cost more than Bananas.} \)
Fact B: \( \text{Bananas cost more than Cherries.} \)
The "bridge" here is Bananas. By linking A and B, you deduce that \( \text{Apples cost more than Cherries.} \)

3. Test for "Must be True"

Ask yourself: "Is there any possible way this conclusion could be wrong based on the facts?" If the answer is no, you have a solid deduction!

Common Types of Deductions in Thinking Skills

In Paper 1 and Paper 3, deductions often fall into a few predictable patterns:

Numerical Deductions

Sometimes the deduction involves a tiny bit of math.
Example: "A bus can hold \( 50 \) people. There are \( 30 \) people already on the bus."
Deduction: There is room for exactly \( 20 \) more people. (Simple, right?)

Exclusion (Elimination)

If there are only three possible winners of a race (Arif, Bella, and Chi) and you find out that Arif and Bella did not win, you can deduce that Chi must be the winner.

Sequence and Order

If you are told that "Task A must be done before Task B" and "Task B must be done before Task C," you can deduce that Task A is the first of the three.

Did You Know?

The 2028 syllabus edition distinguishes between "Simple Deductions" (which you are learning now) and "Complex Deductions" (which involve many more steps and pieces of information). Mastering these simple one-step or two-step links is the essential foundation for the harder problems later in the course!

Common Mistakes to Avoid

Even the best students can get tripped up by these common "logic traps":

• Assuming outside knowledge: Only use the facts given in the question. If the text says "All cats are green," then for the sake of that question, all cats are green!
• The "Could be True" trap: Just because something is possible doesn't mean it’s a deduction. A deduction must be certain.
• Reversing the logic: If "All doctors are smart," you cannot deduce that "All smart people are doctors."

Quick Review: The Deduction Checklist

Before you move on to the next chapter, check if you can do these three things:

1. Identify the Facts: Can you find the specific rules or numbers in the text? \( \checkmark \)
2. Connect the Dots: Can you find a link between two facts to create a new piece of information? \( \checkmark \)
3. Check for Certainty: Is your conclusion necessarily true, or is it just a guess? \( \checkmark \)

Key Takeaway

Simple Deduction is the process of using existing information to uncover a new, certain fact. It is a one-step or two-step logical move that bridges the gap between what you are told and what you need to know to solve a problem.