A variation holds that if ''X'' happened and then ''Y'' did not happen, ''X'' must have prevented ''Y.'' Those disputing a causal relationship sometimes refer to ''X'' as an '''anti-tiger rock''', after the joke that a certain rock must have the magical ability to repel tigers because there are no tigers around. Liberals often justify their favored laws on the basis of what bad things have not happened, without presenting evidence or argument that those things would have happened otherwise. | A variation holds that if ''X'' happened and then ''Y'' did not happen, ''X'' must have prevented ''Y.'' Those disputing a causal relationship sometimes refer to ''X'' as an '''anti-tiger rock''', after the joke that a certain rock must have the magical ability to repel tigers because there are no tigers around. Liberals often justify their favored laws on the basis of what bad things have not happened, without presenting evidence or argument that those things would have happened otherwise. |