Types of Strong Evidence

A: Relevant Evidence-- it SUPPORTS, TELLS MORE ABOUT, or PROVES your claim/reason. It does MORE than just relate to the claim/reason.

Suppose you’re trying to convince your parents to let you stay out an hour later; you argue that you are responsible and they can trust you to make good decisions.

Not relevant: I walk the dog any time you ask, so obviously I can be trusted. (Although doing a household chore shows responsibility, it’s not the kind you need to make good choices about safety.)

Relevant: You have left me home on my own a few times and everything went fine; that proves I am trustworthy. (This is pretty good proof that you can be trusted in situations where you’re unsupervised. Being able to stay out later seems like a logical next step.)

B: Representative Evidence -- It is true A LOT OF THE TIME!

You might provide some fact or story that proves your point, but if it’s only a small number of people or an exception to the rule, it won’t be very convincing.

Let’s say you are trying to convince your principal to make the school start time later. You argue that students will perform better academically if they wake up later.

Not Representative: I can personally focus much better in my later classes. (This might be true for all students, but only one example is not sufficient to prove it.)

Representative: A Northwestern University study of over 2,000 students showed that student test scores rose by 10 percent in schools that moved to a later start time. (Because this study observed over 2,000 students, it is stronger proof that a later start time impacts student achievement.)

C. Credible Evidence: Credible means the evidence comes from a reliable, believable source.

Suppose you are trying to convince a parent to only buy locally grown food. You argue that local food is healthier.

Not Credible: The Food Town employees report that locally grown vegetables have a higher vitamin content than those shipped to stores from across the country. (Although they work with produce, they are not responsible for knowing the nutritional content.)

Credible: The USDA has reported that locally grown vegetables have a higher vitamin content than those shipped to stores from across the country. (It’s the exact same fact, but because it comes from a federal agency rather than store employees, it seems more believable.)

D. Sufficient Evidence: For each assigned reason, do you have SUFFICIENT evidence?

Sufficient evidence means there is enough evidence to prove your point.

You really “sell” your point and you don’t allow “weak spots” for the other team to “shut it down.”

Will they be able to counter argue what you said? How? What information can you provide to prevent that counterargument?

You say: It is going to rain. Your supporting evidence is that it is cloudy.

The other team could counter: Cloudiness does not necessarily mean rain. Sometimes it can be a cloudy day without rain. Clouds could also mean snow or hail, not rain.