[gyepi]

A lot of this depends on the organization, its perceived needs and the personalities involved. No doubt some of the answers you get here will be helpful, but I would focus on the particulars. The first question is whether the organization actually needs a new language or whether you just want to use a new language.

Depending on the environment, the change will bring its own set of difficulties and those will need to be addressed. Sometimes, it's a matter of the people involved. For instance, you are the only one passionate about a new language and others are not or is willing to learn and others are not, etc, then you suddenly have a new problem that may not have existed before, including having to support your colleagues through the transition.

As for arguments, etc, those should arise from your situation. If the current system is not working, make that clear. You may have to repeat yourself to get the point across. But do your homework first. Know what's broken and how your suggestion will fix it. Know the advantages of the current system and the distadvantages of the new one. "Trying something new" does not seem like a good reason; surely there's a reason why you use language X?