A lot of things that try to pass themselves off as science, like homeopathy, clearly aren’t scientific. But it might surprise you to know that there’s no simple checklist or flow chart that lets you separate the scientific from the nice-try-but-not-quites. It’s not for lack of trying; for decades, philosophers worked to figure out how a decidedly human activity could produce such reliable information, but all the big-name thinkers in the field have come up short.

Understanding why they failed is the subject of multiple graduate-level seminar classes. But if you’re just interested in a brief overview, Tim Lewens can help you out.