Fooling people with logic

"We missed the deadline because we chose Java instead of Python. I warned management repeatedly about this." This familiar argument sounds logical, but its premise is deeply flawed, if you can see it.

What the person is claiming to prove is a double implication: "a project can miss a deadline if and only if the choice of the programming language was wrong." But what the person will actually prove is: "if you choose the wrong programming language, your project can miss its deadline." But your project could miss its deadlines because of other reasons too, which remain unexplored.

Frequently, the person giving this argument is not even aware of his own switcheroo. Regardless, it's in your best interest to understand this flaw so that you neither use it, nor allow it to be used on you.