To show the whole dependency tree for each class path, use:
> gradle dependencies
If you are only interested in a particular class path, use (say):
> gradle dependencies --configuration compile
Use the -p option to run on a sub-project.
To show who pulls in a particular dependency onto a particular class path, and how any version conflicts were resolved, use (say):
> gradle dependencyInsight --dependency logback --configuration compile
Note that you can also exclude a dependency from a whole class path (or multiple). Usually this is more reliable than excluding a particular transitive dependency. For example:
configurations.all*.exclude module: "logback-classic"