Why does the verb "was" indicate the fact that no longer exists?

Question

I often see on the Internet one sentence,

He was rich. (He is not rich at present)

Why does the sentence have such an implication? Is it customary only for this sentence to express that meaning? What if I want to say he was rich in the past, but also rich at the present? Should I add some time point to make the tense clear, like he was rich when he was young but still rich when grown up.

My question is that only some past tense sentences, (not all of them) imply a situation that existed in the past but no longer exists at the present according to the habit of expression, right?

See another example,

I didn't sleep well yesterday? (Who knows if I can sleep well tonight?)

I hope I have made myself clear and hope some native speakers can help me.

Answer 1

The simple past tense doesn't have to mean that a statement is no longer true - it just says that it was true at some time in the past.

If the man is no longer rich, we could say He used to be rich or he was formerly rich.

If he is still rich, we could say He was already rich as a young man or He has been rich all his life.

Answer 2

Regarding your second example, "I didn't sleep well yesterday". The speaker is speaking about a period of time that is now over. The word "yesterday" shows that, and that's why they use the past tense. (Mind you, if they intend to sleep at night, they'd more probably have said "last night".) It doesn't carry any implication about how well they think they will sleep in the future. Besides, that is something they won't know and might not want to guess. Someone who is troubled with disrupted sleep might sleep poorly one night and sleep well another night.

I dislike your first example "He was rich.". It's not usual for people to make random past-tense statements like that with no clue as to what period of time they refer to. Let's consider, for example, "He was rich until the financial crash." Why would the speaker say that? It's a fair guess that their point is that the financial crash caused the subject to become poor.

So I see a contrast between these two past-tense statements. One implies that the statement is no longer true; the other doesn't carry any such implication. How come the difference? Typically, we say what we think is relevant in context; we apply the Gricean maxim of relevance. Does a past-tense statement have that implication? It depends. It depends on the nature of what you are talking about.

Another contrasting pair for you:

• It was sunny yesterday afternoon. (Will it be sunny this afternoon? I can't say; bands of cloud come and go.)

• My garden was sunny in the afternoons until they built that tall building across the road. (It's a fair implication that the garden isn't sunny any more because the building blocks the afternoon sun.)

Answer 3

I often see on the Internet one sentence, He was rich (He is not rich at present). Why does the sentence have such an implication?

Because was is the past tense of the verb to be.

The verb to be is used to link the subject’s state with an adjective (or some other part of speech.)

The tense of the verb contains the information to tell you when this state existed:

I am ill = I am currently in a state of illness

I was ill = at some time in the past, I was in a state of illness.

Is it customary only for this sentence to express that meaning?

Yes. The tense of the verb is usually enough to indicate the time that the state occurred.

What if I want to say he was rich in the past, but also rich at the present? Should I add some time point to make the tense clear" like he was rich when he was young but still rich when grown up.

You can use the present perfect with an adverbial phrase of duration: “He has always been rich.

See another example, I didn't sleep well yesterday.

To sleep is not a verb that gives the state of its subject: it is a dynamic verb. The same guidance applies - the tense tells you when the action of the verb occurred:

I sleep = I am currently asleep

I slept = at some time in the past, I was asleep.

I didn't sleep well yesterday? (Who knows if I can sleep well tonight?)

Nobody knows... and neither do you. But you can use the present continuous form:

"I'm not sleeping well" this indicates a recent and unfinished experience and implies that you expect "not sleeping well" to continue.

If you have not been sleeping well for years, then you can use the simple past:

"I do not sleep well."

For very useful information on tenses, see EL&U’s question: How do the tens­es and as­pects in English cor­re­spond tem­po­ral­ly to one an­oth­er?