What is the basis of that theory?

His claim is grounded on solid evidence.

His actions can be understood on the assumption that the hypothesis is correct.

Let's make a hypothesis with a basis.

He set up a candle on the table for dinner.

In Japanese grammar, the hypothetical form is one of the inflectional forms of verbs.

He developed new software to systematize information.

Everyone clapped to cheer for his success.

He makes a living as an artist.

He makes a living as a freelance designer.