Difference between using 'can' and 'could'

[Tan Elaine]

1. You could say "I ate a lot at lunch."

2. You can say "I ate a lot at lunch."

What is the difference between using 'can' and 'could' in the above sentences?

Thanks.

[shroob]

1. You could say "I ate a lot at lunch."

2. You can say "I ate a lot at lunch."

What is the difference between using 'can' and 'could' in the above sentences?

Thanks.

Semi-teacher and native. Since you have no replies, I'll have a go at answering, however, I'm not a full teacher so please be aware of this.

'Could' suggests that there is an ambiguity in the amount of food the person ate. In other words, it may or may not have been a large amount (after all, this varies from person to person).

'Can' suggests that the person definitely ate a lot of food.

[Raymott]

'Could' suggests that there is an ambiguity in the amount of food the person ate. In other words, it may or may not have been a large amount (after all, this varies from person to person).

'Can' suggests that the person definitely ate a lot of food.

I think it's difficult to say this without context (as usual).

Here is a scenario:
"I ate three hamburgers, four large fries, three desserts and a few milkshakes. You could say I ate a lot at lunch." Here, there is no ambiguity at all. But it would be wrong, in most cases, to say, "You can say I ate a lot at lunch."

Here's another scenario:
A: "Your mother is on the phone and wants to know if you're eating well."
B: "You can say I ate a lot at lunch." (Tell her I ate a lot at lunch.)

Can and could are used in their normal way in these sentences.
"You could say ..." is an idiom, meaning roughly: "Without describing everything in detail, it would not be wrong to say ..."

[konungursvia]

The other thing is that "could" is either a past tense of "can" or a conditional mood.