It's whenever you have that feeling of "I just can't decide between these two options", and don't have a strong feeling either way. Quitting a job or ending a

It's whenever you have that feeling of "I just can't decide between these two options", and don't have a strong feeling either way. Quitting a job or ending a relationship can be a marginal decision, if you're not sure you want to do it. Sometimes you're just fed up with your current employer, or there's an obviously good opportunity available - that's not a marginal decision, that's an easy decision. But sometimes there's an opportunity, but you're not sure you want to take it, but it seems intriguing, but it'd be a big risk, but you wonder if you'll regret not taking it, etc. That's a marginal decision, and the type that the article suggests you should take.