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

Distinguish arguments based on evidence from arguments based on warrants
Planning your argument
Part I. Research and writing: from planning to production

Finally, it's important to note that there are two kinds of arguments that readers judge in different ways:

One infers a claim from a reason and warrant. The claim in that kind of argument is believed to be certainly true.

The other bases a claim on reasons based on evidence. The claim in that kind of argument is considered to be probably true.

As paradoxical as it may seem, researchers put more faith in the second kind of argument, the kind based on evidence, than in the first.

This argument presents a claim based on a reason based on evidence:

Needle-exchange programs contribute to increased drug usage._claim When their participants realize that they can avoid the risk of disease from infected needles, they feel encouraged to use more drugs._reasonA study of those who participated in one such program reported that 34% of the participants increased their use of drugs from 1.7 to 2.1 times a week because they said they felt protected from needle-transmitted diseases._evidence

If we consider the evidence to be both sound and sufficient (we might not), then the claim seems reasonable, though by no means certain, because someone might find new and better evidence that contradicts the evidence offered here.

This next argument makes the same claim based on the same reason, but the claim is supported not by evidence but by logic. The claim must be true if the warrant and reason are true and if the reason and claim are valid instances of the warrant:

Needle-exchange programs contribute to increased drug usage._claim When participants realize that they can avoid the risk of disease from infected needles, they feel encouraged to use more drugs._reasonWhenever the consequences of risky behavior are reduced, people engage in it more often._warrant

But we have to believe that the warrant is always true in all cases everywhere, a claim that most of us would—or should—deny. Few of us drive recklessly because cars have seat belts and collapsible steering columns.

All arguments rely on warrants, but readers of a research argument are more likely to trust a claim when it's not inferred from a principle but rather is based on evidence, because no matter how plausible general principles seem, they have too many exceptions, qualifications, and limitations. Those who make claims based on what they think are unassailable principles too often miss those complications, because they are convinced that their principles must be right, regardless of evidence to the contrary, and if their principles are right, so are their inferences. Such arguments are more ideological than factual. So support your claims with as much evidence as you can, even when you think you have the power of logic on your side. Add a warrant to nail down an inference, but base the inference on evidence, as well.