8.3 Drawing Logical Inferences and Conclusions

Drawing inferences is one of the more challenging skills tested on the ECLT. Unlike explicit detail questions where the answer is written word-for-word in the text, inference questions require you to 'read between the lines.' You must take the facts presented in the passage and combine them to reach a logical conclusion that is not explicitly stated.

What is a Valid Inference?

A valid inference is a logical step forward based strictly on the evidence provided. It is a conclusion that must be true (or is highly likely to be true) if the facts in the passage are true. It is absolutely crucial to understand that an inference is not a guess, nor does it rely on your personal knowledge of the world. It must be derived solely from the text.

Identifying Inference Questions

You can easily spot inference questions because they usually contain specific keywords or phrases. When you see these words, know that you will not find the exact answer written in the text; you will have to deduce it.

• "The passage implies that..."
• "It can be inferred from the text that..."
• "Which of the following does the author suggest?"
• "Based on the passage, what is most likely to happen next?"
• "The author probably believes that..."

The Mechanics of Making an Inference

To make a valid inference, follow a simple formula: Fact A (from text) + Fact B (from text) = Logical Conclusion (Inference).

Let's look at a simple example:

• Fact A: Sergeant Miller's uniform was completely soaked.
• Fact B: He had just walked inside from the parade ground, and he didn't have an umbrella.
• Logical Inference: It was raining outside.

The text never explicitly says, "It was raining." However, based on the facts provided, it is the most logical conclusion to draw.

Valid Inference vs. False Assumption Table

Sample Inference Passage Analysis

Passage: During the winter months, operations at the northern airfield become significantly more complex. The specialized de-icing fluid, Formula 4-B, must be applied to all aircraft wings prior to takeoff if the temperature drops below freezing. Due to severe supply chain disruptions this year, the base's reserve of Formula 4-B is currently operating at only 30% of its normal capacity. The base commander has stated that mission-critical flights will take priority until the next resupply shipment arrives in three weeks.

Question 1: It can be inferred from the passage that during the next two weeks: A) The temperature will definitely drop below freezing. B) Non-critical flights may be delayed or cancelled if the weather is cold. C) The base will start using a different type of de-icing fluid. D) The supply chain disruptions will be resolved.

Analysis:

• Option A: We cannot infer the weather forecast. The text only states what happens if it drops below freezing.
• Option B (Correct): We know de-icing fluid is required if it's freezing, supplies are critically low (30%), and mission-critical flights have priority. Therefore, it's highly logical that non-critical flights will suffer if the fluid is needed. Fact (low supply) + Fact (priority for critical flights) = Inference (non-critical flights might not fly).
• Option C: There is no mention of alternative fluids in the text. This is a false assumption.
• Option D: The text says a shipment arrives in three weeks, but we cannot infer the broader supply chain will be entirely fixed in two weeks.

Question 2: What does the passage suggest about Formula 4-B? A) It is inexpensive. B) It is only used at the northern airfield. C) It is essential for safe winter flight operations. D) It is manufactured on the base.

Analysis:

• Option C (Correct): The text states it "must be applied" prior to takeoff in freezing conditions. The word "must" indicates necessity, suggesting it is essential for safety. We don't know the price (A), if it's used elsewhere (B), or where it's made (D).

Strategies for Inference Questions

1. Stick to the Text: The biggest mistake students make is bringing in outside knowledge. Treat the passage like a closed universe. If it's not in the text, you can't use it to make an inference.
2. Eliminate the Extreme: Be wary of answer choices that use absolute words like 'always,' 'never,' 'all,' or 'none' unless the passage firmly supports them. Inferences are often probabilistic (what is 'most likely').
3. Don't Choose Explicit Facts: If a question asks what can be inferred, and one of the answer choices is a direct quote from the passage, it is usually a trap. An inference must be a step beyond what is explicitly written.

Mastering inference requires careful reading and strict logical discipline. Always ask yourself, 'Does the text provide enough evidence to support this conclusion?' If the answer is no, eliminate that choice.