Simple Past Vs. Present Perfect

In this article we will compare the following two tenses:

Simple Past (I did) Vs. Present Perfect (I have done)

Use Case 1: A period of time up to the present Vs. Finished time in the past

Concept 1

When we talk about something that happened in a period of time up to the present - We use the present perfect
Here we tell how long an existing situation has lasted, even if we don’t give a precise length of time.

When we talk about something that happened at a particular, finished time in the past (i.e. for situations that existed for a period of time in the past, but not now) - We use the past simple

Artificial Intelligence has made many major advances this century. (present perfect)
Scientists made some fundamental discoveries in the 18th century. (simple past)

You will be thrilled on seeing the science projects our students have made. (present perfect)
Most of the science projects were excellent. (simple past)

Concept 2

To talk about something that has been recently invented, produced, discovered or written - We use the present perfect.

To talk about something that was invented, produced, discovered or written in the more distant past – We use the past simple.

Scientists have discovered a new characteristic of dark matter. (present perfect)
Dark matter was hypothesized by Fritz Zwicky in 1933. (simple past) 

Use Case 2: When Vs. How long

To talk about ‘when’ a present situation began rather than for ‘how long’ it has been going on - We use the past simple.

I have had this fever for three days now. (focus on how long – so we used present perfect)
I started feeling feverish three days ago. (focus on when – so we used simple past)

Use Case 3: Repeated actions or events

To talk about repeated actions or events - We can use either the present perfect or the past simple.

But there are a couple of fine differences we need to keep in mind:

• If we think that the action/event might happen again – We use the present perfect. Often to emphasise it further, we use phrases such as ‘so far’ and ‘up to now’.
• If we think that the action/event is finished (i.e. it won’t happen again) - We use the past simple

Compare the following sentences:

Dan Brown has written 5 novels and I have read all, except for the last one. (present perfect – because he may write another novel.)
Dan Brown wrote 5 novels before he got disenchanted with writing. (simple past – because action of writing novels is over.)

Use Case 4: States

To talk about states - We can use either the present perfect or the past simple.

But there are a couple of fine differences we need to keep in mind:

• To talk about a state that existed in the past and still exists now – We use the present perfect.
• To talk about a state that no longer exists - We use the past simple

Compare the following sentences:

I have known him since he was a toddler. (present perfect – because my state of knowing him still exists now.)
I knew him when we was a kid. (simple past – because my state of knowing him no longer exists)

Use Case 5

If past time is given in a sentence, the sentence must be in simple past tense and never in present perfect tense.

I have come yesterday. (incorrect; present perfect)
I came yesterday. (correct; simple past)

Use Case 6: Since

Concept 1

We use since to talk about a period that started at some point in the past and continues until the present time. This is why we often use since with the present perfect.

Since 2018 I have lived in a small condo apartment near my office. (have lived – present perfect)

Jake has been unfit since the last series. (has been – present perfect)

Concept 2

In a sentence which includes a since-clause, the usual pattern is for the since-clause to contain a past simple, and the main clause to contain a present perfect.

So, with ‘since’ we follow the following patterns:

Pattern 1: present perfect tense + since + simple past tense

I have not met her since she joined XLRI.
(have not met – present perfect; joined - simple past).

Pattern 2: perfect form of any modal + since + simple past tense

She may have relocated since he last met her.
(may have relocated - modal in perfect form; met – simple past)

Use Case 7: News reports

In news reports:

• We often introduce events with the present perfect, and
• We provide the details using the past simple.

The SpaceX space shuttle has returned safely to earth. It landed in Kazakhstan yesterday.
(has returned – present perfect; landed – simple past)

Use Case 8: Adverbs used with these tenses

Concept 1

With some of those time adverbs that connect the past to the present – We use present perfect (rather than the simple past).

For example: just, lately, already, since, so far, still, up to now, yet.

Setu cannot go out to play. He just recovered from his illness. (incorrect; simple past)
Setu cannot go out to play. He has just recovered from his illness. (correct; present perfect)

Did you see our dentist lately? (incorrect; simple past)
Have you seen our dentist lately? (correct; present perfect)

Concept 2

With time adverbs that talk about finished periods of time – We use simple past (rather than the present perfect).

For example: in, at, on, once, ago, last, then, yesterday.

Stephan Hawking has died in 2018. (incorrect; present perfect)
Stephan Hawking died in 2018. (correct; simple past)

Concept 3

Some adverbs of time can be used with both the present perfect and the past simple.

For example: before, for, and recently.

We had the van for ten years. (we no longer have it; simple past)
We have had this van for five years. (we still have it; present perfect)

Extra Books and Tools

If you prefer to learn via books, or want some good English Grammar books for reference purposes, you may read this article which enlists some of the books recommended by us.