First, consider the following cases:

  • You want to ask someone out.
  • You have three job offers, one from Amazon, one from Tesla, and one from Google.
  • You’re not sure whether to help out someone or not.
  • You’re a physicist and you can’t prove whether the particle you’re looking for exists or not.

These cases are each very different from the other.

They all belong to different domains and types of knowledge, and require different modes of actions.

When you’re doing physics, the way you generate and acquire knowledge is very different from your other daily activities.

In physics, for instance, you’re looking for evidence via rigorous methods of investigation and analysis.

You have the proper tools for that too, and if you don’t, chances are someone is trying to build them.

The process is lengthy, and slow.

But when you’re deciding to help someone, choose which offer to accept, or ask someone to marry you, chances are you have to act based on the belief that you made the right decision.

Two Categories of Belief

We can think of the mentioned cases as belonging to two different categories of belief, then:

Epistemic: concerned with knowledge in the empirical, scientific sense.

Practical: concerned with the myriad decisions we have to make on a daily basis, often without having enough time or resources to look for ‘sufficient evidence.’

In the case of epistemic beliefs, philosopher William James argues that, obviously, we should NOT believe based on insufficient evidence.

If you think your calculations show that there’s another particle out there, you have to prove it, even if it takes forever. It’s not an urgent matter. It can wait.

In the case of practical beliefs, James argues that we are justified to believe based on insufficient evidence.

But only when we are confronted with a genuine option. Think moral dilemmas, life-changing and big career decisions etc.

Genuine Options

We are justified to believe based on insufficient evidence when the option is GENUINE. Meaning the option is live, forced and momentous:

LIVE: your belief has to be at least about something plausible. I believe Jeff Bezos will choose me to go to Space. Well, if I don’t have millions to pay for the trip now, I’m delusional, barring a miracle of course.

FORCED: A forced option is one where we can’t just NOT make a decision: If I have the millions, I will either have to choose to pay to go or decide not to.

MOMENTOUS: A momentous option is one that might have significant consequences on our lives: if I really, really want to go to Space, then the fact that I have to choose to go or not is momentous.