Prior probabilities with no experience in a domain at all is an incoherent notion, since that implies you don’t know what the words you’re using even refer to. Priors include all prior knowledge, including knowledge about the general class of problems like the one you’re trying to eyeball a prior for.
If you’re asked to perform experiments on finding out what tapirs eat—and you don’t know what tapirs even are, except that they eat something apparently, judging by the formulation of the problem—you’re already going to assign a prior of ~0 of ‘they eat candy wrappers and rocks and are poisoned by everything and anything else, including non-candy-wrapper plastics and objects made of stone’, because you have prior information on what ‘eating’ refers to and how it tends to work. You’re probably going to assign a high prior probability to the guess that tapirs are animals, and on the basis of that assign a high prior probability to them being either herbivores, omnivores or carnivores—or insectivores, unless you include that as carnivores—since that’s what you know most animals are.
Priors are all prior information. It would be thoroughly irrational of you to give the tapirs candy wrappers and then when they didn’t eat them, assume it was the wrong brand and start trying different ones.
For additional clarification on what priors mean, imagine that if you didn’t manage to give the tapirs something they actually are willing to eat within 24 hours, your family is going to be executed.
In that situation, what’s the rational thing to do? Are you going to start with metal sheets, car tires and ceramic pots, or are you going to start trying different kinds of animal food?
Prior probabilities with no experience in a domain at all is an incoherent notion, since that implies you don’t know what the words you’re using even refer to. Priors include all prior knowledge, including knowledge about the general class of problems like the one you’re trying to eyeball a prior for.
If you’re asked to perform experiments on finding out what tapirs eat—and you don’t know what tapirs even are, except that they eat something apparently, judging by the formulation of the problem—you’re already going to assign a prior of ~0 of ‘they eat candy wrappers and rocks and are poisoned by everything and anything else, including non-candy-wrapper plastics and objects made of stone’, because you have prior information on what ‘eating’ refers to and how it tends to work. You’re probably going to assign a high prior probability to the guess that tapirs are animals, and on the basis of that assign a high prior probability to them being either herbivores, omnivores or carnivores—or insectivores, unless you include that as carnivores—since that’s what you know most animals are.
Priors are all prior information. It would be thoroughly irrational of you to give the tapirs candy wrappers and then when they didn’t eat them, assume it was the wrong brand and start trying different ones.
For additional clarification on what priors mean, imagine that if you didn’t manage to give the tapirs something they actually are willing to eat within 24 hours, your family is going to be executed.
In that situation, what’s the rational thing to do? Are you going to start with metal sheets, car tires and ceramic pots, or are you going to start trying different kinds of animal food?