This question is posed and addressed by two of the most influential contributors to modern cosmology: 

George Ellis & Joe Silk

Nature Comment 16 December 2014

http://www.nature.com/news/scientific-method-defend-the-integrity-of-physics-1.16535

Their commentary on this is excellent and has been discussed widely on the Nature website.  I thought that readers who do not normally go to that site might like to have the opportunity of joining this important discussion here on ResearchGate.

I would also recommend reading the discussion that follows from that article.  So let's hear what you think!

http://www.nature.com/news/scientific-method-defend-the-integrity-of-physics-1.16535