I sometimes play a game with my cat, Cleo. I stand around the corner from her, just out of sight. She starts to sneak towards me. When I poke my head around the corner to look at her, she freezes. When I pull back, she carries on sneaking. Eventually, she pounces on my ankles.

In my mind, we’re playing Statues – the children’s game in which the aim is to sneak up on someone without that person seeing you move. But Cleo can’t be thinking of it that way. So, what’s she thinking? Why does she freeze when my head pops around the corner?

Here’s an obvious answer. She’s trying to attack my ankles. She stops when I stick my head out because she knows I can see her, and knows that if I see her coming I’ll know she’s coming, and she’ll lose the element of surprise.

This obvious answer assumes that Cleo is a mindreader. Now, I don’t mean by this that she’s telepathic. Psychologists and philosophers use the term ‘mindreader’ to refer to someone with the ability to ascribe mental states to others. I’m a mindreader in this sense, and so are you – because we can make judgments about what others are thinking, feeling, seeing, and so on. Our answer assumes that Cleo is a mindreader because it involves her making a judgment about what I can see (her approaching), and about what I know (an attack is imminent).