For instance, saying “string theory is true” is a claim. Saying “string theory isn’t true.” Is not a claim.
actually they are both claims.
Well of course they are technically both claiming something but in the context of needing to provide proof, the latter claim is really just a claim negating the prior claim, thus does not carry the burden of proof. I suppose I could have worded it better but I wanted to get my point across as simply as possible.