"Have forgotten" or "forgot"?

Question

I'm walking out of a bar and I'm putting my hand in my pocket, and I can't find my wallet.

So it's better to say "I have forgotten my wallet" or "I forgot my wallet" ?

Answer 1

Grammatically, either version is fine for OP's context, but most people would probably go for the shorter Simple Past version most of the time (if only because it is shorter and simpler).

The difference is really one of fine nuance. Present Perfect focuses more explicitly on your current state - that of being without your wallet due to (past) forgetfulness. Simple Past actually carries the same meaning in OP's exact context, but it's important to note that this is a contextual implication.

Consider a slightly different scenario where the speaker is paying his drinks bill with a credit card, but forgetfulness strikes in the form of a senior moment at the "Enter PIN number" stage. Credible things he might say to the barman to explain the problem include...

1) I have (more commonly, I've) forgotten my PIN
2) I forgot my PIN
3) I forget my PIN

I think in that situation the Present Perfect would probably be most likely. Note that in practice the Simple Present (#3) doesn't actually occur very often with the specific verb to forget. We don't tend to think of forgetting as a "continuous" activity - it's usually the case that at some unspecified point in the (usually, very recent) past the speaker realised he couldn't recall some relevant information because it had already been forgotten. Thus to some people it might sound a little odd to use Present Tense to say you're currently forgetting something - which almost implies that immediately prior to speaking, you hadn't yet forgotten it.

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Short Answer:

Both are perfectly natural, and it would be stretching a point to say either is "better" in most contexts. But as ever - for simplicity, most learners would do better to avoid Perfect forms unless they're absolutely necessary (the KISS principle).

Answer 2

As @SovereignSun pointed out, they are both perfectly fine. It just depends on what tense you want to use.

The Present Perfect Tense (I have forgotten) is formed with a present tense form of "to have" (I have) plus the past participle of the verb, which can be either regular or irregular in form see here which in the case of forgotten the verb is a past participle of the irregular verb "forget".

The Past Tense or Simple Past Tense (I forgot) indicates that an action is in the past relative to the speaker or writer.

Both phrases are gramatically correct because they follow the rules of each part of their relevant tenses.

Answer 3

Both are appropriate. I'd probably use the simple past just because it's a tiny bit shorter and more definite and I'd want to get back in the bar as quickly as possible to retrieve my wallet.

To get some insight into the difference, consider a conversation with your roommate the next morning. If you noticed forgetting your wallet when you came out of the bar, you'd say "I forgot my wallet" when talking about it the next morning. That's because the episode is over. Especially if you successfully retrieved your wallet, you would not use the present perfect. You'd say "Last night, I forgot my wallet at the bar, but luckily I noticed right as we were leaving, and I went back in and found it."

Now suppose that you didn't notice forgetting your wallet when you left the bar. You're talking the next morning with your roommate and you notice right then. Now both simple past and present perfect are appropriate, because the story of your forgotten wallet is not yet over. "Oh no! I've forgotten my wallet! I must have left it at the bar!" You're describing the current situation as part of an ongoing story that began last night. Because the present perfect frames the past event as part of some process that continues unbroken to the present and perhaps into the future, choosing the present perfect also suggests that you have some hope that you could still recover your wallet.