[danielam]

I know you're being terse, but I hate the way the word "doubt" is used here so I'll take the opportunity to pontificate.

Doubt, too, must be justified as much as certainty. We tend not to doubt something until there is a reason to doubt it and certainty grows with corroborating evidence. Furthermore, if I were to say that I have a coin in my right hand, you would have neither doubt nor certainty about the claim because given your knowledge there is no reason to doubt that I had such a coin but likewise no evidence that I do.

Doubt that does not obey such a process becomes very unproductive and indeed science is most productive when it abides by a falliblistic principle of economy.