This is when we support a conclusion by appealing to a person who is not an authority on the subject. Or, it is when we appeal to an authority with whom other authorities disagree.
1) Peace is the best strategy because Einstein said so.
Note: this is fallacious because Einstein was an expert in physics, not political science.
2) You should take those vitamins because Brad Pitt said they are the best.
3) God does not exist because Stephen Hawking said so.
4) God exists because the Pope and Francis Collins said so.
5) Psychiatry is rubbish because Dr. Smith said so.
If you appeal to an authority, you should appeal to the appropriate authority. For example, you should appeal to an authority in physics if you are debating a topic in physics. This sounds simple, but many intelligent people confuse areas of expertise.
However, even appeals to appropriate authorities can be fallacious. This is because it is not the person that makes a claim true, it is the evidence and arguments. For example, Einstein did not make space and time relative. Rather, he discovered it. It is the evidence he presented that supports claims for the relativity of space and time, not his authority.
How to avoid
One approach is to not trust anything on authority.
Of course, this is very difficult to do because we cannot be experts in everything. And so I trust my doctor on some medical matters, and I trust the community of physicists on other matters. The best we can do is carefully research authorities before trusting them.
- Create or find a few examples of this fallacy.
- List some authorities you trust and explain why you trust them.
- See above examples.
- I trust the computer technician when she diagnoses my computer problems. I trust my doctor on most issues, but may occasionally seek a second doctor’s opinion.
In Introduction to Logic (2010), Harry Gensler observed that he trusts his calculator and computer for mathematical calculations.