Anybody who habitually writes or says “the way in which” is a pretentious fool. Nine times out of ten, this silly phrase can be replaced with “how”. The same is true for the plural version, “the ways in which”. If you really do need a concept of the way or ways that something has happened, rather than just of how it has happened, you can say “the way that” or “the ways that”. You never need to use “the way in which”. Not ever.
I’ll say one thing for the phrase, though: for those who value precision and clarity, it marks a person’s writing or talk as not worth paying attention to. If you have sympathy with the person, you may even feel a twang of “Will you tell them, or shall I?” It’s as if they have a string of toilet paper stuck into the band of their trousers or skirt and they don’t realise. I really enjoy reading what a person has written, or listening to them talk, when they know what they’re talking about, and when they’re expounding on it because they want to help me satisfy my wish to improve my understanding, my wish to learn something from them. I don’t enjoy listening to those who dress their writing and speech up with unnecessary supposed finery that carries no content and doesn’t assist with communication either. “The way in which” is an ugly and dispensable phrase that doesn’t make the scribbler or utterer sound knowledgeable or willing to impart their knowledge at all. It’s worse than them asking “yah” or smacking their lips three times at the end of every sentence.
If you find that you’ve adopted this phrase, please drop it. It’s never too late.
If you’re stubborn and you want to suggest an example of a sentence in which “the way in which” is the clearest phrase to use – clearer than “how”, clearer than the alternatives, clearer than recasting – that’s great. It shows you’re thinking about what I wrote. I’ll be surprised if you can come up with one. If you can, please post a comment and let me know what it is.