How to support design decisions? [closed]

Question

There are bad design decisions.
On the same pitch, being a senior engineer can sometimes be hard. Youngsters have awesome and radical ideas, which a senior engineer wonders whether will work on the field, and if it is worth spending all that effort. Experience suggests that these are short-term solutions are very expensive in the long run. However, it might be hard to convince otherwise.

How does one go about in this scenario? Patterns are a good start, however, it takes a little experience to figure out where to apply a pattern, as a newbie might restate the problem to fit the pattern. Also, patterns do not help at coarser/component levels. Another idea is to refer to a good design that works in the field, and is outside the organization. The problem here is that sometimes drawing a parallel might be hard. Are there any other ideas?