There is no longer a such thing as a "just" war.
Also, please keep examples and references fairly recent (19th century, at the earliest) as the debate is on the concept of a "just" war in modern society.
Just war: a war that is deemed to be morally or theologically justifiable.
War: a state of armed conflict between different nations or states or different groups within a nation or state.
To put into broader terms, a "just" war would be a war in which the taking of human lives , and damage to humanity and the earth itself is justified by some principle or another. Wars are waged for trivial political and economic motivations, expansionist ideals, religious disagreements, and sundry other reasons, none of which reasons can justify the taking of human lives, as well as the destruction of land and homes.
Example #1: Crimean War (1853-1856)
The Crimean War is largely regarded as the first modern war. This war was Russia against the Ottoman Empire, France, Great Britain and Sardinia. France, Russia, and Great Britain were all competing for the control of access to the religious sites in the Holy Land. This ultimately boils down to influence in the Middle East, particularly Turkey. Also during this time, Russia had grown into a considerable military power. This left Britain to worry that Russia would expand to the point of holding power over the Mediterranean Sea.
There were over 500,000 military casualties in total. These people died so their countries could hope to achieve influence in Turkey and the Holy Lands.
Example #2: World War II (1939-1945)
This is inarguably the most infamous war in the history of the world, involving countries from all across the globe, hence the apt name of the war.
Weimar Germany was angered by the terms of the Treaty of Versailles, which created the Covenant of the League of Nations, outlined Germany's disarmament, exacted massive reparation payments from Germany, and forced Germany to cede large tracts of territory to various European nation-states. Germans felt these terms were both extreme and unfair. German leader Adolf Hitler was also expansionist, seeking world domination with the Third Reich. This 1000 year German Empire also involved a racist utopia consisting of only those of the Aryan race (blonde hair, blue eyes), and the systematic elimination of all others, subsequently causing the Holocaust. Japan entered the war with the notion of becoming a major colonial power.
It is a commonly held belief that America entered World War II for the following reasons: (1) the need to protect the U.S. from a direct invasion by Germany and/or Japan; (2) the moral imperative to stop the domination of the tyrannies of Nazi Germany and imperial Japan in the cause of furthering democracy; and (3) the need to do all we could to rescue the Jews who were being annihilated by the Nazis. This, however, was not truly the case. In actuality, the United States had four underlying reasons to enter the global war: (1) they had long been involved in a clash of imperialisms with Japan (the attack on Pearl Harbor had been a last-ditch resort for the Japanese; in summer and early autumn of 1941, the Japanese Prime Minister wanted to meet with President Roosevelt to try to defuse the conflict, and Roosevelt refused to do so); (2) the U.S. had been growing ever closer to Britain, and had already been aiding their cause in the way for a while; (3) prior to the outbreak of the war, American business interests were heavily invested in the Hitler regime, and these businesses realized it would bode poorly for them if Germany became an economic free agent; and (4) American military and business elites stood to benefit greatly from entering the war, as they could move to a place of power and influence within the federal government. These reasons are far less noble and "just" than what the general public is led to believe.
Many believe that the United States wanted to put an end to the annihilation of Jews, and that is one reason they entered the war; this is not the case. America had a tepid response to the Holocaust. The U.S. immigration system severely limited the number of German Jews admitted during the Nazi years to about 26,000 annually, but even that quota was less than 25% filled during most of the Hitler era, as the Roosevelt administration piled on so many extra requirements for would-be immigrants. Roosevelt also suggested that the best answer to the "Jewish question" was to "spread the Jews thin across the world." It is clear that the rescuing of the Jewish people was not high on the list of American priorities.
After six years of bloodshed, the war would end. A total of 63,185,500 people lost their lives, including 10 million Jews, gypsies, Jehovah's witnesses, homosexuals, Slavs, Soviet POWs, and people with mental and physical disabilities who perished in German concentration camps. Countless atrocities to humanity, as well as millions of deaths and damage to cities and land, occurred over expansionism, racism, economic motivations, and political disagreements.
Example #3: War in Afghanistan (2001-present)
On October 7, 2001, after the 9/11 attacks in America, President George W. Bush declared war on Afghanistan to "liberate" the country from the terrorist network and Al Qaeda, find Osama Bin Laden, and dismantle the reigning Taliban regime.  A picture is painted for the public that the security of America and the Free World alike necessitates increased activity in Afghanistan. Contrary to popular belief, the security of the American nation is not directly tied to this country in the Middle East. The building and protection of oil and gas pipelines in Afghanistan has been a key objective of US policy since before the 2001 American invasion and occupation of the country. The initial American objectives have virtually been completed: Al Qaeda is virtually vanquished and the Taliban now poses little threat to America. Yet, in spite of this, Americans are still dying each day for the true objective: oil.
Close to 15,000 civilians have been killed in the war, along with over 2,000 American troops. These numbers are still climbing today, and climb to protect oil pipelines.
These wars cannot be justified. Economics, expansionism, racism, need for political dominance, need for natural resources--none of these can justify the taking of millions upon millions of human lives, and the damage it does to the physical world and the souls of those involved.
JUST WAR: a war that is deemed to be morally or theologically justifiable & which led to improvement of human society.
But Just war theory is a doctrine which is getting evolved from many centuries now and almost all religious and ethnic society have the concept of just war in there respective manuscripts. For instance, Christian societies have been evolving the concept & one of the major writings of Hinduism i.e, Bhagvad Geeta justifies the war of Mahabharata. Modern just war guidance involves both the decision to go to war (jus ad bellum) and how to fight one (jus in bello). This latter set of criteria focuses on proportionality (how much force is used), targeting (avoiding non-combatants), and means (avoiding certain classes of weapons). The problem with just war theory is that it is too philosophical to implement. Also, the ethical reasons of war i.e, The Right or wrong depends on the perspective. To simplify this, I would reiterate a famous phrase
'One man's terrorist is another man's freedom fighter.'
A majorly accepted definition of just war is
What is a Just War?
A war is only just if it is fought for a reason that is justified, and that carries sufficient moral weight. The country that wishes to use military force must demonstrate that there is a just cause to do so.
Six conditions must be satisfied for a war to be considered just:
1. The war must be for a just cause.
2. The war must be lawfully declared by a lawful authority.
3. The intention behind the war must be good.
4. All other ways of resolving the problem should have been tried first.
5. There must be a reasonable chance of success.
6. The means used must be in proportion to the end that the war seeks to achieve.
How should a Just War be fought?
A war that starts as a Just War may stop being a Just War if the means used to wage it are inappropriate.
1. Innocent people and non-combatants should not be harmed.
2. Only appropriate force should be used.
This applies to both the sort of force, and how much force is used.
3. Internationally agreed conventions regulating war must be obeyed.
I would like to extend the point on the war as well. I agree to the below point
"Wars are waged for trivial political and economic motivations, expansionist ideals, religious disagreements, and sundry other reasons, none of which reasons can justify the taking of human lives, as well as the destruction of land and homes."
But some other reasons of wars have been nationalism, rights in society, Equality & others.
I would agree with my friend in the notion that not all wars are justifiable wars. Most of the wars are resultants of expansionism & other reasons put forth. My opinion is that not all wars follow the just war principles but there have been armed conflicts in past which were justifiable. Further discussing on the carefully selected examples put forth by my friend 'The Instigator'.
1. Crimean War -
I have not much idea about the proceedings of the war but whatever overview I have the war seems to be a result of expansionist ambitions of all major powers involved. And they do not seem to be justified.
2. World War 2 -
No one can justify the World war 2 and its casualties. Till now it is the most terrifying human experience with wars. But what we are considering here is the Holocaust, the casualties of wars. The World war got triggered when Britain & France Declared war on Germany for its armed campaign against Poland. I personally think that the Declaration of war at that point of time by Britain & France on Germany was totally justifiable. We can debate on this point as well whether it was justified or not.
3. War on Afghanistan
Afghanistan was in shatters before US invasion. It was a living hell from the 1980s itself and through the 90s under the rule of Taliban. The society under Taliban govt was a Patriarchal medieval society. I think an explosion and then light is better than decades of darkness in which Afghanistan was living in & continued to live in. The basic justification behind the was was an act which was unjustified.
Some more of the instances in my judgement are close to just wars:
There is a long list of revolutions occurred which in one way or another arose for the basic rights of people and society whether its nationalism or equality. American war of revolution carved out a nation which in today's times is at the helm of human society. The French revolution initiated the rise of social and political upheaval of France and in a way on modern history worldwide. Different set of independent revolutions against the imperial rules in the 20th century.
2. American Civil War
The conflict which resulted in most heinous crimes of human society i.e, Slavery.
3. Napoleonic wars.
The conflict between different coalitions of monarchies against the French Empire. These wars led to many developments such as rise of nationalism among various ethnicity as well as abolition of HRE.
The just war is possible but as its outline is very subjective so a lot of factors comes into play while deciding whether a war is justifiable or not.
But Human society is evolved to be so free minded and coherent & some justifiable wars have a strong role to play in this.
"A just war is in the long run far better for a man's soul than the most prosperous peace" - Theodore Roosevelt
"Is it morally acceptable to murder one hundred innocent people in the process of catching a serial killer who has murdered ten people?" - Michel Templet
1. Very rarely in wars are innocent people and non-combatants not harmed. Civilians are often the unfortunate casualties of war. Some examples:
2. There is no concrete definition on what "appropriate force" is. For instance, the Germans may have considered their constant bombings of England to be "appropriate force”. Aside from this, the use of “appropriate force” does not make a war anymore “just” or noble than the use of excessive force.
3. Again, to obey internationally agreed conventions regulating war cannot make a war more or less “just”. It is proper “etiquette”, if you will, but it cannot make the war “just” or unjust.
Response to “just” wars:
1. Revolutions: A problem with revolutions is that they often happen immediately, with little diplomatic relations beforehand. My opponent states that “all other ways of resolving the problem should be tried first”. This is not the case with revolutions. Violence is the first objective. My opponent uses the example of the American Revolution. A timeline of major events leading up to the revolt:
While Americans did attempt a boycott, and the Boston Tea Party was a nonviolent act of rebellion, we see that there were no diplomatic relations or discussions beforehand, thus ruling out that *all* other ways of resolving the problem were tried first.
(One a more personal note, I find it extremely hard to see any violent act of revolution after learning of Gandhi’s Salt March and other nonviolent resistances.)
2. The American Civil War was truly not as “just” as it is portrayed to be. This war was initially not about slavery—in fact, Lincoln’s issuing of the Emancipation Proclamation was more about war strategy than the freeing of slaves. While slavery was, indeed, a point of conflict between the Union and the Confederacy, the war was truly fought over state's rights and the limits of federal power in a union of states, and slavery was a specific issue of a perceived violation of a state's rights, over which the country went to war. Two percent of the American population suffered death or maiming—all to end a dispute about states’ rights.
3. I admittedly know very little about the Napoleonic Wars, except that Napoleon desired conquest of neighboring countries (expansionism). But if, as my opponent said, the end outcomes were a rise in nationalism and the dissolution of the Holy Roman Empire, I cannot buy into the thought that the 4 million deaths as a result of this war were justified.
Response to: "A just war is in the long run far better for a man's soul than the most prosperous peace" - Theodore Roosevelt
No war can be better—be it for the soul or anything else—than peace. War, with all its bloodshed and atrocities, can never be better than peace. War is neither noble nor necessary. It is a crime that humanity commits against itself. There is nothing to gain by murdering the innocent and destroying the earth itself. There is no principle divine or noble enough to justify an act of war.
“He who joyfully marches to music rank and file, has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would surely suffice. This disgrace to civilization should be done away with at once. Heroism at command, how violently I hate all this, how despicable and ignoble war is; I would rather be torn to shreds than be a part of so base an action. It is my conviction that killing under the cloak of war is nothing but an act of murder.” – Albert Einstein
"I object to violence because when it appears to do good, the good is only temporary; the evil it does is permanent." - Mahatma Gandhi
"There is no glory in battle worth the blood it costs." -Dwight D. Eisenhower
This has been a very interesting discussion, and I want to sincerely thank my opponent debating with me on an issue that I believe very strongly in.
anonymous.user01 forfeited this round.