błąd logiczny in English:

I want to show you fallacy of this argument.

And the fallacy comes from idealizing a past that we have forgotten about.

Dealing with the phenomena of interest, he exposes the old fallacy that the rate depends upon the amount of money in a country.

There's this thing called the planning fallacy.

fallacy = a mistaken belief or idea

Because that fallacy is so ridiculous, I cannot understand how you believe it!

It's a fallacy to believe that attracting large companies from the outside is the key.