Logical Reasoning Foundations: Claims, Reasons, Premises, and Conclusions

Four Building Blocks: Claim, Reason, Premise, Conclusion

When people argue, they typically do two things: they take a position and they support it. The vocabulary can be confusing because different pairs of terms overlap:

• Claim: a statement someone puts forward as true (or as something to do). It is the “point” being asserted.
• Reason: a statement offered to support a claim. It answers “Why think that?”
• Conclusion: the specific claim the argument is trying to establish.
• Premise: a specific reason (or piece of evidence) used to support the conclusion.

How the pairs relate: claim vs. reason is a general, everyday way to talk about arguing; conclusion vs. premise is the more precise “argument map” way to label the same roles. In most arguments, the conclusion is the main claim, and the premises are the reasons.

Two quick cautions

• Not every claim is a conclusion. People make many claims while talking; only some are the “therefore” point of a specific argument.
• Reasons can be multiple and layered. A reason can itself be supported by another reason (a “sub-reason”), creating a chain.

How to Tell What’s a Premise and What’s a Conclusion

Step-by-step: label the roles

1. Find the “point.” Ask: “What is this person trying to get me to believe or do?” That candidate is the conclusion.
2. Find the support. Ask: “What are they offering as support for that point?” Those are premises.
3. Check with a ‘therefore’ test. If you can naturally insert therefore before a sentence, it may be the conclusion. If you can insert because before a sentence, it may be a premise.
4. Watch for indicator words (helpful but not required):
   • Conclusion indicators: therefore, so, thus, hence, that’s why, it follows that
   • Premise indicators: because, since, given that, due to, for

Example: same content, different roles

Version A: “The sidewalks are icy, so you should walk slowly.”

• Premise: The sidewalks are icy.
• Conclusion: You should walk slowly.

Version B: “You should walk slowly because the sidewalks are icy.”

• Same roles as Version A; the word order changed, not the structure.

Version C: “You should walk slowly. If you walk slowly, you’re less likely to fall. The sidewalks are icy.”

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• Conclusion: You should walk slowly.
• Premises: If you walk slowly, you’re less likely to fall. The sidewalks are icy.

Notice how the conclusion is the recommendation; the other sentences are doing supporting work.

One Sentence, Different Jobs: Premise in One Context, Conclusion in Another

A sentence’s role depends on what it is supporting (or being supported by). The same sentence can be a conclusion in one argument and a premise in another.

Example chain (the same sentence switches roles)

Argument 1: “The forecast says heavy rain this afternoon, so you should bring an umbrella.”

• Premise: The forecast says heavy rain this afternoon.
• Conclusion: You should bring an umbrella.

Argument 2: “You should bring an umbrella, because staying dry will help you avoid getting chilled.”

• Premise: Staying dry will help you avoid getting chilled.
• Conclusion: You should bring an umbrella.

In both arguments, “You should bring an umbrella” is the conclusion. Now watch it become a premise:

Argument 3: “If you should bring an umbrella, then you should leave five minutes early to grab it. You should bring an umbrella. So you should leave five minutes early.”

• Premise 1: If you should bring an umbrella, then you should leave five minutes early to grab it.
• Premise 2: You should bring an umbrella.
• Conclusion: You should leave five minutes early.

Here, the sentence “You should bring an umbrella” is no longer the final point; it is a supporting step toward a new conclusion.

Practical tip: ask “What is this sentence doing here?”

Don’t label a sentence by its topic (“umbrella sentence”) or by how confident it sounds. Label it by its function: is it being used to support something else (premise), or is it what the support is trying to establish (conclusion)?

Mini-Drills: Identify Premises and Conclusions

For each snippet, identify the conclusion and the premise(s). Some have one premise; some have two. Try the “therefore/because” test.

Drill 1

“You should bring an umbrella because the forecast says heavy rain.”

• Conclusion: ________
• Premise(s): ________

Drill 2

“The meeting starts at 9, so we must leave by 8:30.”

• Conclusion: ________
• Premise(s): ________

Drill 3

“Since the printer is out of ink, we probably can’t print the handouts today.”

• Conclusion: ________
• Premise(s): ________

Drill 4

“If we skip lunch, we’ll be cranky. We should eat now.”

• Conclusion: ________
• Premise(s): ________

Drill 5 (role shift)

“You should bring an umbrella. If you should bring an umbrella, you should take a bag. So you should take a bag.”

• Conclusion: ________
• Premise(s): ________
• Which sentence is a premise here but could be a conclusion in a different argument?: ________

Answer key (hide and check)

Conclusion Strength: Must, Should, Probably (and What You’re Committed To)

Arguments don’t just differ in what they conclude; they differ in how strongly they conclude it. Words like must, should, and probably signal different levels of commitment. This matters because it changes what would count as a successful objection.

Three common strength levels

Same premises, different strength

Premise: “Dark clouds are moving in and the weather app shows a 70% chance of rain.”

• Weak-to-moderate conclusion: “It will probably rain.”
• Stronger conclusion: “It will rain.”
• Very strong conclusion: “It must rain.”

The premises fit “probably” well. They might support “it will rain” in everyday talk, but “must” overcommits: it claims certainty that the premises don’t provide.

Practical step: match strength to support

1. Underline the conclusion’s strength word (must/should/probably/etc.).
2. Ask what would make it false. If one realistic scenario would make it false, “must” is risky.
3. Adjust the conclusion to what the premises can actually carry: swap “must” to “probably,” or specify conditions (e.g., “If the forecast is accurate, it will rain”).

Mini-drill: tune the conclusion

For each, decide whether the strength word fits the premise. If not, rewrite the conclusion with a better fit.

• Premise: “I saw one review saying the restaurant was bad.” Conclusion: “The restaurant is definitely bad.”
• Premise: “The train is delayed and you have a strict start time.” Conclusion: “You should message your team that you may be late.”
• Premise: “This route is usually faster at this hour.” Conclusion: “We must take this route.”