it would have been possible

Question

a. It would have been possible for him to steal the money.

Could that sentence mean

b. He could have stolen the money. ?

To me (a) means that if something else had or had not happened, then it would have been possible for him to steal the money, but that condition was not fulfilled and at the end it was not possible for him to steal the money. It doesn't mean that he decided not to steal the money.

(b) means that he refrained from stealing the money. It was possible for him to do it, but he decided not to.

Many thanks

Answer 1

Without further context you can't infer much from either sentence.

In particular in both cases it is possible that they did steal the money, and it possible that they did not steal the money.

If they did not steal the money, it is possible in both cases that they chose not to, and it is possible that they were able to at some point, but something happened and then they were not able

And you can't infer that the money was stolen at all. You could use either sentence whether or not the money is missing.

The choice of "would have been possible", would seem to be emphatic, to contrast explicitly with a previously held assumption that it was impossible. I doesn't seem to have a different meaning.

Answer 2

According to the Cambridge Dictionary, possible can have two meanings, relating to ability and certainty. can/could also has both of these meanings (plus other meanings), so it is pointless to try to explain the meaning of sentence a using sentence b.

It would have been possible for him to steal the money.

Generally, when used with to, the meaning of possible is about ability: he had the skills and opportunity to steal the money, but nothing is implied about whether he did steal the money.

is possible relates to an opportunity now.

was possible relates to an opportunity in the past.

would have been also places the opportunity in the past, and suggests that some other factors, possibly clarified in previous or following sentences, are involved. For example, it could be followed by a but clause

It would have been possible for him to steal the money, but he wouldn't have been able to hide it.

When used with that, it's about certainty: he may have stolen the money.

It is possible that he stole the money.