Support your claim with reasons and evidence - Planning your argument - Part I. Research and writing: from planning to production

A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Support your claim with reasons and evidence
Planning your argument
Part I. Research and writing: from planning to production

It may seem obvious that you must back up a claim with reasons and evidence, but it's easy to confuse those two words because we often use them as if they meant the same thing:

What reasons do you base your claim on?

What evidence do you base your claim on?

But they mean different things:

We think up logical reasons, but we collect hard evidence; we don't collect hard reasons and think up logical evidence. And we base reasons on evidence; we don't base evidence on reasons.

A reason is abstract, and you don't have to cite its source (if you thought of it). Evidence usually comes from outside your mind, so you must always cite its source, even if you found it through your own observation or experiment; then you must show what you did to find it.

Reasons need the support of evidence; evidence should need no support beyond a reference to a reliable source.

The problem is that what you think is a true fact and therefore hard evidence, your readers might not. For example, suppose a researcher offers this claim and reason:

Early Alamo stories reflected values already in the American character.claim The story almost instantly became a legend of American heroic sacrifice.reason

To support that reason, she offers this “hard” evidence:

Soon after the battle, many newspapers used the story to celebrate our heroic national character.evidence

If readers accept that statement as a fact, they may accept it as evidence. But skeptical readers, the kind you should expect (even hope for), are likely to ask How soon is “soon?” How many is “many?” Which papers? In news stories or editorials? What exactly did they say? How many papers didn't mention it?

To be sure, readers may accept a claim based only on a reason, if that reason seems self-evidently true or is from a trusted authority:

We are all created equal,reason so no one has a natural right to govern us.claim

In fact, instructors in introductory courses often accept reasons supported only by what authoritative sources say: Wilson says X about religious masks, Yang says Y, Schmidt says Z. But in advanced work, readers expect more. They want evidence drawn not from a secondary source but from primary sources or your own observation.

Review your storyboard: Can you support each reason with what your readers will think is evidence of the right kind, quantity, and quality and is appropriate to their field? Might your readers think that what you offer as evidence needs more support? Or a better source? If so, you must find more data or acknowledge the limits of what you have.

Your claim, reasons, and evidence make up the core of your argument, but it needs at least one more element, maybe two.