Support for the Ukrainian government in the war against the Russian invasion has been justified, in Italian (and European) public opinion, with the need to defend an aggrieved people: parallels have been drawn between the situation in Ukraine and the partisan struggle against Nazi-fascism, and it is has been insisted that peace cannot be built without re-establishing the right violated by Putin's government. This article points out that such a justification has two weaknesses that make it difficult to accept. The first is an oversimplification: being based on crude conceptual pairs (good/evil, aggressors/offenders), the argument of the need to defend a people under attack does not allow one to grasp the complexity of the situation and, therefore, to propose effective solutions. The second weakness is the incoherence between the means one wants to use (war) and the objective one wants to achieve (the defence of the Ukrainian people): an incoherence due to the fact that war - especially if protracted in time and conducted with highly destructive weapons - necessarily implies for the people suffering it a burden of death and destruction at least comparable to the evils of foreign domination. In conclusion, the article reflects on the duty of men and women of thought, which is not to declare war just (or inevitable, or holy), but to remind the ruling classes and public opinions of democratic countries of the need to put an end to violence, to put the solution back to negotiations and reason, to try to build bridges between peoples despite everything.