Why is there so little debate in Congress?

[Angel of Death]

I find it striking how there is hardly any actual interaction going on between members in either of the two chambers; the sessions mostly consist of members making long monologues and if any questions are asked, they're usually just part of a friendly setup between members who are already on the same side on the issue. Is this culture just a result of having a two-party presidential system where positions and votes are not expected to be subject to persuasion on the floor? It's certainly not a given that any deliberative assembly must work this way.

[The world will shine with light in our nightmare]

Members of Congress are very unlikely to change their minds on most issues unless they're extremely weak moderate heroes.  Debates in Congress are mostly for show, not for convincing the other party to support your bill or agenda.  If we had third party members in Congress, people still wouldn't be likely to change their minds, but debate would be much more interesting.

[Meeker]

Not all of the floor debate is irrelevant, at least in the House. For amendments dealing with issues that aren't super politicized or well-known, lots of Representatives and staffers pay attention to what is being said on the floor, as well as who is speaking (the latter is probably more important).