Logical Thinking · Lesson 1 of 4

Premises, conclusions, and the two ways an argument fails

Write the premises and the conclusion on separate lines. Half the problems become visible immediately.

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An argument has premises (the reasons) and a conclusion (what they are meant to support). Written out plainly, most arguments become much easier to assess, because you can attack each part separately.

There are exactly two ways an argument can fail. The premises can be false, or the conclusion can fail to follow even if they are true. Confusing these two produces most unproductive disagreement — you dispute the facts while the other person disputes the logic, and neither of you notices.

Consistency is the cheapest check available. Hold your positions side by side and see whether they can all be true at once. Contradictions are common, not because people are careless, but because positions are adopted one at a time in different moods and never laid out together.

See it happen

"Remote teams ship slower, so we should bring everyone back in."

The read that arrives on its own

It matches what I have seen. Makes sense.

The same situation, with this idea

Premise 1: remote teams ship slower. Premise 2 (unstated): our slowness is caused by being remote. Conclusion: return to the office. Premise 1 might be true on average and still not be true here.

What changed

Written on separate lines, the gap is visible in seconds: the conclusion needs the second premise, and the second premise was never offered.

The takeaway

Write the premises and the conclusion on separate lines. Half the problems become visible immediately.

Easy to take the wrong way

Attacking the conclusion when the problem is the premise. If you disagree, say which line you are disagreeing with — otherwise the argument just gets repeated louder.

Try this

Take an argument you made recently. Write it as: because A, and because B, therefore C. See whether C really follows.