Added README.

README.markdown

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+# GOGAR
+
+GOGAR ("the game of giving and asking for reasons") is a simplified
+model of the discursive scorekeeping practice described in Robert
+Brandom's book *Making It Explicit* (Cambridge: Harvard University
+Press, 1994). It is designed to help illustrate the way agents'
+attributions of commitments and entitlements to each other is
+affected by the speech acts of making, disavowing, and challenging
+assertions.
+
+GOGAR currently models only a part of the practice described in
+Chapter 3 of *Making It Explicit*, and it makes many simplifying
+assumptions. For example, it assumes that all the agents are in
+earshot of each other, so that testimonial inheritance of
+entitlements is universal.
+
+[Try GOGAR on the web!](http://johnmacfarlane.net:9094/)
+
+The current version of GOGAR is a single Ruby script,
+[gogar.rb](gogar.rb). After downloading it, you can run it with the
+following command:
+
+    ruby gogar.rb
+
+You may need to install [Ruby](http://www.ruby-lang.org) first.
+There's an installer for Windows
+[here](http://rubyforge.org/frs/?group_id=167). Mac OSX comes
+with a version of ruby.
+
+You can also run GOGAR as a web application, as follows:
+
+    ruby gogar.rb -w
+
+By default, GOGAR will run on port 9094, so point your browser to
+<http://localhost:9094/> and you should see it.  An alternative port
+can be specified as follows:
+
+    ruby gogar.rb -w 7000
+
+GOGAR carries no warranties of any kind.
+