Invocation of the "right to national defense" to support the recruitment and slaughter of workers in defense of one national state - or aspiring state - against another.
Historical context of defensism
The 1914 war, the first imperialist world war, marks a point of no return in the development of imperialism and the system's entry into its historical decadence.
Every national capital sells the war as the ultimate solution to the pending tasks of the bourgeois revolution of the previous century. Germany takes up the banner of putting an end to tsarism, the last bastion of feudal reaction in Europe; France and Britain claim to represent democracy against the barbaric Prussian system and, together with the US, will defend the right to self-determination as a tool for national liberation in Central and Eastern Europe. Without the slightest shame, the war is labelled the war to end all wars.
But the reality is that the gigantic organization of capitalist production has become a machine of annihilation. Millions of workers die en masse in the fields of Europe in a war organized in the Taylorist way, by battle plan and stopwatch. The defensist discourse, the invocation of the right to national defense against a foreign invasion, is the ultimate imperialist argument: every bourgeoisie defending itself against its neighbors amounts to nothing but total slaughter.
The main figures of the Second International and the leadership of its parties and unions will turn defensism, once the war has begun, into a way of encouraging the workers to go on sacrificing themselves en masse and killing each other until "a democratic peace without annexations or indemnities" is achieved.
The Marxist critique of defensism by Rosa Luxemburg and Lenin
Inevitably, the invocation of the "right to national defense" will go hand in hand with a whole lot of empty verbiage invoking a non-existent "International Law" and endless discussions about who is the "aggressor" or the "guilty party". But...
Whatever the truth about the direct responsibility for the outbreak of the war, one thing is certain: the war that has produced this chaos is the outcome of imperialism, of the attempt by the capitalist classes of every country to satisfy their greed for profit through the exploitation of human labor and of the natural resources of the entire world.
Zimmerwald Manifesto against the war. L. D. Trotsky, 1915
Or in the words of Rosa Luxemburg:
In the discussion about the general causes of the war and its significance, it is not a question of solving the problem of who is "guilty". Germany certainly does not have the slightest right to speak of a war of defense, but France and England have no greater justification. They too are protecting not their national existence, but their world political existence, their old colonial possessions, from the attacks of the German upstart.
Rosa Luxemburg. The Crisis of Social Democracy (Junius Pamphlet), 1916
Rosa Luxemburg's underlying argument is that imperialism is a stage of capitalism as a whole. Even if, for some time, some countries might have remained relatively on the margins, the entry into a stage of world wars would express by itself the impossibility of a development of national capital independent of the conditions of imperialism during the new phase of decadence into which the system was sinking.
If the term "national" has remained, its real content and its function have turned into their opposite; it serves only as a miserable cover for imperialist aspirations and as the battle cry of their rivalries, as the only and last ideological means of securing the adherence of the popular masses and their playing the role of cannon fodder in imperialist wars.
Rosa Luxemburg. The Crisis of Social Democracy (Junius Pamphlet), 1916
As she would insist in another pamphlet that same year:
In this era of unleashed imperialism there can be no more national wars. National interests serve only as a pretext for putting the popular masses at the service of their mortal enemy: imperialism.
Rosa Luxemburg. The Tasks of Social Democracy, 1916
The same thing that makes the overcoming of capitalism an immediate necessity - capitalism's entry into decadence - makes it reactionary to create new national states or to defend existing ones in one way or another. Only revolutionary defeatism now represents the interests of the workers in inter-bourgeois conflicts.
The result of the great war is that it is impossible for the capitalist classes to get out of their difficulties as long as they remain in power. We now understand the truth contained in the phrase first formulated by Marx and Engels as the scientific basis of socialism, in the great charter of our movement, the Communist Manifesto. Socialism, they said, will become a historical necessity.
Speech at the Founding Congress of the Communist Party of Germany. Rosa Luxemburg, 1919
Revolutionary defeatism means nothing other than turning the imperialist war into civil war between classes.
In order to dupe the proletariat and divert its attention from the only truly emancipatory war, that is, the civil war against the bourgeoisie, both of its "own" country and of "foreign" ones, the bourgeoisie of each country strives, with lying phrases about patriotism, to extol the significance of "its" national war and to assure us that it aims at defeating the adversary not for the sake of plunder and territorial conquest, but for the sake of the "liberation" of all other peoples except its own. (…)
The transformation of the present imperialist war into a civil war is the only correct proletarian slogan, indicated by the experience of the Commune, outlined in the Basel resolution (1912) and derived from all the conditions of an imperialist war among highly developed bourgeois countries. However great the difficulties of such a transformation may seem at one time or another, socialists will never renounce systematic, persistent and unremitting preparatory work in this direction, now that the war has become a fact.
Only by following this path will the proletariat be able to free itself from its dependence on the chauvinist bourgeoisie and take, in one form or another and more or less rapidly, decisive steps towards genuine freedom for the nations and towards socialism.
"The War and Russian Social-Democracy". Lenin, 1914