Forms of evidence

Questions to consider

Argument is a powerful, fundamental method through which we learn about the world: we ask questions, gather evidence, then use reasoning to connect the evidence and follow it to a conclusion.

But as we've talked about a few different forms of evidence, you might have noticed they all have the same problem:

  • How do you know a piece of evidence is actually true?
  • And if it's true, how do you know it's being accurately interpreted and represented?

As we've seen in this lesson, it's a real problem! There's no easy answer!

In fact, there are whole bodies of philosophy, science, and law devoted to trying to answer the question of how we can ever really know anything or be certain about anything.

Epistemology laser cat meme
Epistemology is the branch of philosophy concerned with how we know anything at all.

But it's not all bad!

There are ways of knowing things and proving things well enough that we can get through our daily lives, and actually do some things pretty well!

If we didn't have lots of solid evidence about the world, we wouldn't be able to create phones & satellites, laptops & bridges, antibiotics & MRI machines, and we wouldn't have functioning family, economic, legal, and political systems.

It's not impossible to know things, it's just that evaluating evidence is complex enough that it belongs in its own lesson.

In the meantime, we'll leave you with a few tips.

Here are three questions that will help you evaluate the quality of a piece of evidence in its own right:

  • Is there enough evidence?
  • Is it typical (or is it an outlier)?
  • Is it accurate (or is it wrong in some way)?

You might not have enough information or expertise to evaluate the evidence itself, so you can also try to evaluate the source:

  • Who provided the evidence? (If it's personal, who experienced it? If it's a study, who collected and published it? If it's a survey, who asked and answered it?)
  • Why did they provide this evidence? (Are there personal or structural motivations or incentives that would make you doubt the evidence?)
  • Do you trust their selection, representation, and interpretation of the evidence?

You can ask similar credential and motivation questions about yourself, too!

  • What expertise do you have to interpret or evaluate this evidence?
  • What are you already looking for when you encounter this evidence?
  • What do you get from interpreting this evidence one way or another?

We can easily get evidence wrong ourselves, whether because we don't have the expertise or we consciously or unconsciously want to believe something in particular, and we collect and interpret evidence in a way that fits what we want.

You can ask questions to evaluate how the evidence fits into the context of the argument:

  • Is the evidence relevant to the argument? (Or is it beside the point?)
  • Is there more important evidence that should be considered?

Asking these questions is easy—answering them is hard!

That's because most are valuational questions, which means they are based on criteria, and those criteria need to be defined by someone, and those definitions will be different based on context!

For example, the standards of evidence a family would apply when arguing about whether or not to get a pet crab are different to the standards a government would use when deciding whether or not to build a space elevator. (At least, we hope.)

But, for now, they will have to do!

Let's wrap up with a checkpoint piece!

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