Of all the questionable premises that a debater may find himself/herself in, relativity is probably the most disputed one. Debaters often appeal to the 'everything-is-relative-perception-is-illusion' argument in order to demonstrate the limitations of the perspective put forward by his/her opponents. But how much compelling is such a stance?
Suppose you are debating for the motion, 'One man's freedom fighter is another man's terrorist.' You might be tempted to point out that both freedom fighter and terrorists are relative terms, and can easily change meanings depending on which side you are on. This is especially true for terrorism, because it's a controversial term with no internationally agreed single definiton.
Arguments such as the one given above has their roots in Relativism, the philosophical view that the meaning and value of human beliefs and behaviors have no absolute reference. Some relativists claim that humans can understand and evaluate beliefs and behaviors only in terms of their historical or cultural context. The term also refers to ethical relativism, which states that right or wrong are a function of the moral teachings of a society. It holds that an act is right when it is approved by the society one belongs to, and wrong when it is not.
But this theory has been criticized resoundingly because of the conceptual and moral difficulties it presents. Does this mean that the white lynch mobs from the southern states of USA were morally right in executing black people brutally from 1882-1930, simply on the grounds that such acts were particularly prevalent in the cultural and historical context of those times? Does this also justify genocides carried out by a group against minorities? Such a theory makes it impossible to appeal to objective values and criteria for adjudicating disputes between different groups belonging to different societies.
Coming back to the example of the motion given earlier, your opponents can make your argument regarding relativity fall flat on its face because of the its inherent practical difficulties, as can be seen from the examples given above. Your opponent may emphasize the necessity of having a universal definition of the word terrorism, so that proper punitive measures can be implemented against violations of justice and human rights. He/she may also argue that although there is no single definition of the word 'terrorism'; countries have reached consensus regarding some basic elements of terrorism For example it is generally agreed that terrorism is violence against civilians to achieve political or ideological objectives by creating fear. Most common definitions of terrorism include only those acts which are intended to create fear (terror), are perpetrated for an ideological goal (as opposed to a lone attack), and deliberately target or disregard the safety of non-combatants. This goes on to show that a group who correspond with these criteria qualify for the universal definition of terrorists, regardless of whether some people perceive them to be as freedom fighters.
The only way you can topple your opponents arguments in cases like these is to provide substantial evidence contrary to his/her assertions. Because your stance is difficult to prove conceptually, you have to resort to reality. And reality is chockfull with examples that can come to your aid. John Brown, the famous American abolitionist, led the killing of civilians in his raid on Harper's Ferry to ignite a slave revolt. Martin McGuinness, commander of the Derry Brigade of the Provisional IRA (Irish Republican Army), is considered by many Irish people as a valiant freedom fighter, in spite of talking about the "legal and moral right of the IRA to kill a British soldier at any time." Nobel Prize winner Yasser Arafat has been charged in the cold-blooded assassination of U.S. Ambassador Cleo Noel in the Sudan in 1973 and of carrying out terrorist activities against Israel, but nonetheless has a special place in the hearts of Palestinians. Nelson Mandela, another Nobel Peace Prize winner was sentenced to life imprisonment on Robben for plotting terror to overthrow the regime. Ahmed Ben Bella led Algeria's war of independence, in which terror was the insurgents' weapon to counter the torture carried out by the French. Numerous examples can be given to prove that no single definition of terrorism can be universal, because of political complications and ambiguities that inevitable accompany specific conflicts.
Relativity is a concept fraught with confusion, but can be used because the evidence of moral and political diversity around the globe is undisputable. However, arguments regarding relativity have to be backed up by ample proof.