Welcome to another addition of the "Rules of Style" by Ralph Lauren. Remember, most of the time these "rules" should be taken as suggestions, rather than hard-fast musts. The key is to develop your own sense of style, but I think having the rules under your belt is still helpful. Here are my thoughts for this week:
Why they chose this to be a rule baffles me. First of all it's not a rule, it's more of a thought/preference. Second, I don't really agree with it, and let me tell you why.
I think sport coats, cashmere cardigans, and denim jackets all have different uses in one's wardrobe. Yes, all three can work with a dress shirt and tie, but the occasions that you can wear each item will probably be a bit different. What I'm saying is that a denim jacket or cardigan isn't quite a 1:1 substitute for a sport coat. Sport coats will certainly be the most formal of the three. Cardigans come next, and then denim jackets.
Denim jackets are considered very casual, so when you pair a tie and dress shirt with one, you're basically dressing your outfit down. With a cardigan, I'd say you're keeping your outfit neutral in formality, and with a sport coat, you're dressing the outfit up. So in all, I think all 3 combinations can be great, but know they are not true substitutes.
Personally I think this is a pretty solid look, but borderline preppy. I don't actually own any repp ties for that reason, and in case you don't know what a repp tie is, here's an article about them. Anyway, a classic oxford shirt paired with a repp tie is a solid and safe look to go with if you want to showcase your "American" sense of style.
Oh, and clearly you can tell this is Ralph Lauren's rules of style by this picture- check out that tiny polo design on the guy's shirt.
I love the four-in-hand knot. In fact, I love it so much, it's the knot I use about 95% of the time. The other 5% is divided between the half-windsor and full-windsor. It's easy to tie, versatile (can work for pretty much any occasion) and really looks great with most tie widths. In case you don't know how to tie this knot, here's something to help you.
So to recap:
Cardigans, denim jackets, and sport coats all work well with a tie & dress shirt. The formality will likely differ with each piece though.
If you want to put together a solid American look, just pair an oxford shirt with a repp tie. Though preppy, it can't go wrong.
The four-in-hand knot is almost the only knot you really need to know. Easy to tie, and works for basically all situations.
Hope these help; peace easy my friends.