SCP Foundation

Basically, it's a recording of the Spandau Ballet song "True", but when played while looking at an idea, no matter if it is real or not, you "know this much is true". Basically, it convinces you that something is true. You also start using evidence that would be able to describe that the concept is true, even if the evidence cannot be found using any scientific process or cannot be known by the person who listened to the song.

when played while looking at an idea

What does this mean? Like, someone writes down an idea of theirs and you read it while the recording plays?

You also start using evidence that would be able to describe that the concept is true, even if the evidence cannot be found using any scientific process or cannot be known by the person who listened to the song.

Is this evidence made up out of thin air, evidence that manifests itself, or evidence that already exists but can't prove the idea right? I'm a bit confused

It's certainly a start but it's so vague and undefined that you could go a million different places with it. Approaching the idea as it is right now would make for something pretty boring and uninteresting. What angle are you going to approach this from? How would you develop it? Where do you think, in-universe, this anomaly comes from and why it manifests? It's just… there, as it is, and runs a little bit close to a lot of anomalies right now. One angle to take this idea to is explored heavily in SCP-946, so there's already something there that's been done.