What Are the Evidence & Arguments for Ratings Inflation?

I hear often on the forums that ELO ratings have inflated since Fischer's time.  What are the evidence and arguments behind this assertion?

Thank you for posting this, as it has been on my mind.  In a lot of ways, I'm back in the '60's, in that I played intensely then, as a teenager, and have only played sporadically since then.  I do know that back then I had a rating of 1400, and when I played some in the '80's, I seemd to be at 1550 in no time.

More to the point, though, I remember when Fischer's cracking 2700 (and I believe he was only a bit above that) seemed astonishing. I just looked at world ratings, and now he'd be about 45th.  Really?  Hard to believe.  Or have computers just made so many players better?

A correction -- I now see that Fischer reached around 2785 at the end, and that makes me feel better.  I had remembered him topping out at about 2720.