I am totally unfamiliar with this name, but it appears he was a major player in the development of Skepticism, and we need to know enough about him to fit him into the big picture:
Like Sextus Empiricus it appears that Aenesidemus wrote in Greek rather than Latin. I wish I were not getting the impression that the most radical forms of skepticism were much more appealing to the Greek mind than to the Roman mind.
This appears to be key:
The ten modes of Aenesidemus
The reasons for doubt are given in the form of the ten "tropes" (also known as ten modes of Aenesidemus or ten tropes of Aenesidemus) that represent reasons for epoché (suspension of judgment). :[5]
- (1) different animals manifest different impressions;
- (2) similar differences are seen among individual people;
- (3) even for the same person, sense-given data are self-contradictory,
- (4) sense data vary from time to time with physical changes, and
- (5) sense-data vary according to local relations;
- (6) and (7) objects are known only indirectly through the medium of air, moisture, &c., and are in a condition of perpetual change in colour, temperature, size and motion;
- (8) all perceptions are relative and interact one upon another;
- (9) Our impressions become less deep by repetition and custom; and
- (10) all people are brought up with different beliefs, under different laws and social conditions.
Aenesidemus argues that truth varies infinitely under circumstances whose relative weight cannot be accurately gauged. There is, therefore, no absolute knowledge, for everyone has different perceptions, and, further, arranges and groups data in methods peculiar to themselves; so that the sum total is a quantity with a purely subjective validity.[5]