The most important thing that I learned

[BloodSweatTears]

Are the use of the simple past in the first clause and of the present perfect in the second one correct given that in the first one I am speaking of a specific period of time whereas there is not specific time period in the second?

The most important thing I learned in school is...

The most important thing I have learn is...

 

[bhaisahab]

"The most important thing I have learned is..." is possible in the right context.

 

[emsr2d2]

Or "... I have learnt is ...".

 

[PaulMatthews]

Are the use of the simple past in the first clause and of the present perfect in the second one correct given that in the first one I am speaking of a specific period of time whereas there is not specific time period in the second?

The most important thing I learned in school is...

The most important thing I have learned is...

Essentially yes.

If you are no longer attending school, the simple past The most important thing I learned in school is... would be correct. (the period of your learning is located wholly in the past)

If you are still attending school, then the perfect The most important thing I have learned is... would be correct. (the present perfect here is seen as having some current relevance, relevance to the present.)

 

[BloodSweatTears]

And would it be correct to say The most important thing I have learned is... without still attending school, with the implicit meaning put into parenthesis: The most important thing I have learned (in my life) is...?

 

[PaulMatthews]

And would it be correct to say The most important thing I have learned is... without still attending school, with the implicit meaning put into parenthesis: The most important thing I have learned (in my life) is...?

Sorry, I skimmed your second example and assumed it was also referring to school. As Piscean said, the answer is yes, and the reason is because you are still living. Your life/learning still has some current relevance (presumably!) If you said The most important thing I learned in my life ..., that might be interpreted as meaning you must be dead, or almost!

 

[Tdol]

If you said The most important thing I learned in my life ..., that might be interpreted as meaning you must be dead, or almost!

The first interpretation would make little sense outside a zombie film. The second works- a speaker could use it on their deathbed.

 

[PaulMatthews]

The first interpretation would make little sense outside a zombie film. The second works- a speaker could use it on their deathbed.

Oh, come on! It was obviously supposed to be humorous, and to make a point at the same time. You're nit-picking.

 

[Tdol]

My apologies- we do get the odd real-life pedant here, and I seem to have fallen victim to Poe's law. uppydog:uppydog:uppydog:uppydog:uppydog:uppydog:uppydog: