Some things seem like they just can't be coincidences. They seem to call for explanation. If you toss a coin many times and it repeatedly lands heads, that might be an example. Philosophers have used this idea to argue for some far-reaching conclusions, such as that there aren't really any numbers, that other universes exist and, more famously, that an all-powerful god exists. But what does it mean for something to call for explanation? And, are these arguments good ones?