pro hominem

Latin: argumentum pro hominem; English: argument from authority

The general form:

1. X believes P
2. (If X believes P, P is true)
3. Therefore P is true

X in the argument is a single or group of authorities who endorse P. According to Good Reasoning Matters!¹, the argument is good if X has:

• Credentials that are relevant to the claim in question
• No biases that are likely to interfere with the assessment of the claim
• The claim in question concerns an area in which there is wide agreement among the relevant experts
• The claim concerns an area of knowledge in which consensus is possible

An argument from authority could be described as a second order argument or argument by transitivity because the argument implies that the expert has a good reason for believing the claim. Arguments from authority can be particularly dangerous in science if they allows outdated theories to hide behind their decorated discoverers. It should be noted that the credentials of experts can be very difficult to judge for matters in which one cannot get a PhD. An example of a bad argument from authority is any celebrity endorsement.

Contrast ad hominem arguments.

1: Note: this is an appeal to the authority of the authors of Good Reasoning Matters!, the textbook for a course I took at Trent University called Practical Reasoning: Leo Groarke, Christopher Tindale (the teacher of said course), and Linda Fisher.