Philo the Dialectician facts for kids

Philo the Dialectician was an ancient Greek philosopher. He lived around 300 BC. He was part of the Megarian (Dialectical) school of thought. People sometimes called him Philo of Megara. We don't know where he was born. He is famous for his debates with his teacher, Diodorus Cronus. They argued about what "possible" means. They also debated how to tell if "if...then..." statements were true.

Philo's Life

We don't know much about Philo's life. He was a student of Diodorus Cronus. He was also a friend of Zeno. Zeno started a philosophy called Stoicism. Diogenes Laërtius wrote that Zeno admired Philo. Zeno was younger than Philo. He studied logic very carefully with him.

Philo's Writings

Philo wrote a book called Menexenus. In this book, he mentioned Diodorus's five daughters. All of them were skilled in dialectic, which is a form of logical debate. Another philosopher named Chrysippus wrote books that responded to Philo's ideas. One was about "Philo's Work on Meanings." The other was about "Philo's Work on Moods."

Philo's Philosophy

Philo often debated with his teacher Diodorus. They disagreed on two main ideas. These were the meaning of "possible" and how to decide if "if...then..." statements were true.

What is "Possible"?

Diodorus believed that something was "possible" only if it was true or would become true. For him, "possible" meant the same as "necessary."

Philo had a different idea. He said "possible" meant something could be true by its very nature. It didn't matter if it ever actually happened. For example, Philo would say, "This piece of wood can burn." This is possible, even if the wood stays at the bottom of the ocean forever. It still has the ability to burn.

Truth in "If...Then..." Statements

Both Philo and Diodorus wanted to find rules for "if...then..." statements. These are called conditional statements. Each philosopher used their own idea of "possible" to figure this out.

Philo believed an "if...then..." statement was true unless one specific thing happened. That one thing was if the first part (the antecedent) was true, but the second part (the consequent) was false.

Let's look at some examples based on Philo's rule:

• If something true happens, then something else true happens. (Example: If the sun is out, then it is daytime.) Philo says this is true.
• If something false happens, then something true happens. (Example: If it is raining cats, then the sky is blue.) Philo says this is true.
• If something false happens, then something else false happens. (Example: If pigs fly, then dogs meow.) Philo says this is true.

Philo said only one type of "if...then..." statement was false:

• If something true happens, then something false happens. (Example: If the sun is out, then it is nighttime.) Philo says this is false.

This way of thinking about "if...then..." statements is very similar to how modern logic works today.

Diodorus had a stricter rule. He said an "if...then..." statement was only true if the first part could never lead to a false second part.

About 100 years later, the Stoic philosopher Chrysippus looked at the ideas of both Philo and Diodorus. He disagreed with some of their assumptions.

See also

In Spanish: Filón de Megara para niños