# Is a dissimilar event less likely to happen?

Suppose an event occurs in the world that you deem to be dissimilar enough to all other events that have ever happened in the world to consider it unique. Does this imply it is less likely to happen than some other event that is considered similar to other events.

Let’s consider A = the class of events that have atleast one other event similar to it. Let’s consider B = the class of events that have no other events similar to it

If B is a class of one, and A is a class of millions, wouldn’t that imply a unique event is less likely? Or is this a fallacy?

My more general question is whether or not coming across some event that you process as way differently from other events implies a lower probability. If this is a fallacy, what is it called?

• You need to clarify what you mean by similar. May 14 at 19:45
• Let’s assume for the purposes of this example dissimilar means your brain just finding it to be dissimilar. Like coming across a black swan in a world full of white swans May 14 at 19:49
• Give an example. May 14 at 20:20
• please let it go. is there not a book you can read on these sorts of questions?
– user65994
May 15 at 1:24
• In a world where only one black swan exists amongst a million white swans, you might calculate probabilities of encountering one. What you cannot do though, is calculate a probability of the black swan existing at all (other than '1'?), because we have no way of knowing whether the world could have existed in any other way. The sample size is one. This theme continually crops up in your questions, which frequently fail to acknowledge this. The fallacy is a non-sequitur. The fact a rare event happens does not imply it was less than inevitable (although it may have been uninevitable). May 15 at 7:08