Strong Evidence Should Be a Fact, Not an Opinion

Strong evidence in support of a claim should be a fact or a direct quote from a text. Simply giving additional opinions in support of a claim makes for weak support of the claim.

Here’s an example:

Claim

Americans can help preserve natural resources by becoming vegetarians.

Strong Evidence	According to a UN report, food production in countries like the US has a “higher environmental impact” than in countries that consume less meat.
Weak: Opinion, Not a Fact	Choosing to become a vegetarian is the responsible, ethical choice for the future of the planet.

Remember

Sometimes, readers will disguise an opinion in the form of a question, but this is also weak evidence because it is not a fact.

Here’s another example:

Claim

Placing orcas in captivity is inhumane.

Strong Evidence	In captivity, orcas are unable to travel the 62 miles per day that they sometimes swim in the wild.
Weak: Opinion, Not a Fact	Wouldn't you be traumatized if you were taken from the wild and forced to live in a tiny enclosure?