I saw him run vs. I saw him running

I saw him run.
I saw him running.

What is the difference between the sentences?



The first sentence focuses on the entire event while the second one stresses the action or process of the running itself. You would need more context to understand the difference better.

For example:

I saw him run away. (You focus on the result, on the fact that he disappeared).
I saw him running away. (You describe the process of running. You focus on the running itself. In the second sentence it’s not clear whether or not he actually disappeared.).


While I agree with Torsten, I would like to explain the difference thus: the first (bare infinitive) indicates that the speaker has witnessed the whole activity (running) while the second (progressive participle) indicates that the speaker had only a glimpse (part) of the activity (running) at some point in time during which the activity was in progress.