\ragged commands
LaTeX provides commands \raggedright and \raggedleft, but
none to cancel their effect. The \centering command is
implemented in the same way as the \ragged* commands, and suffers
in the same way.
The following code (to be inserted in a package of your own, or as internal LaTeX code) defines a command that restores flush justification at both margins:
\def\flushboth{%
\let\\\@normalcr
\@rightskip\z@skip \rightskip\@rightskip
\leftskip\z@skip
\parindent 1.5em\relax}
There’s a problem with the setting of \parindent in the code: it’s
necessary because both the \ragged commands set \parindent to
zero, but the setting isn’t a constant of nature: documents using a
standard LaTeX class with twocolumn option will have
1.0em by default, and there’s no knowing what you (or some
other class) will have done.
Any but a really old copy of Martin Schröder’s ragged2e
package has a \justifying command to match its
versions of the LaTeX ‘ragged’ commands. The
package also provides a justify environment, which
permits areas of justified text in a larger area which is ragged.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=flushboth