When is it reasonable or justifiable to accept a claim based simply on the testimony or authority of another?

It is reasonable to accept a claim based on the testimony or authority of another when the individual or source has established credibility, expertise, or a track record of reliability in the relevant field. Additionally, if the claim is consistent with well-supported evidence or aligns with established knowledge, it may be justifiable to trust it. Context also matters; claims about specialized topics may require reliance on experts, while common knowledge may not. Ultimately, critical thinking and a degree of skepticism should guide such acceptance.