A/CONF.189/PC.2/22 page 8 18. With the exception of the European Convention of Human Rights, all the relevant international instruments establish the same obligation to guarantee free and compulsory education, but in the context of the general obligation inherent in the right to education.14 The latter is a matter of concern to the present study only as it relates to the problem of racial discrimination and religious intolerance. It should, however, be noted that, in article 13, paragraph 2, of the Covenant, the wording of this obligation warrants attention because it is directly linked to the objectives and content of education as provided for by article 13, paragraph 1 (“2. The States parties to the present Covenant recognize that, with a view to achieving the full realization of this right:”). As one author has stated, international instruments thus have “a core content” which must guarantee absolute minimum entitlements in respect of access to education, but must also provide for minimum entitlements in respect of the content of education and interculturalism.15 19. Several studies on the scope of the principle of non-discrimination in the education of minorities and indigenous children have rightly shown that the principle of non-discrimination must be handled with a great deal of care. Differences of result in the educational system are not always attributable to the discrimination to which minority groups might be subject, but to various handicaps which affect both the majority and minorities (family, economic and social situations, etc.).16 As one study rightly concludes, the result is that: “In cases where the majority has no access to quality education, it seems legitimate to give priority to equality and non-discrimination rather than to the respect and promotion of diversity” (E/CN.4/Sub.2/AC.5/2000/WP.4, para. 24). (b) The question of separate systems of education 20. Public schools and compulsory schooling imply that young people of different origins attend the same schools. As a Swiss expert rightly indicates, “If children developed separately at school, they would continue to do so later on in society and this would intensify social, cultural and economic inequalities. Ghettos would spring up and violence would threaten social peace”.17 21. In strictly legal terms, the lawfulness of separate schools is still open to discussion (these are schools or classes set up in public education; they must therefore be distinguished from private schools). They may be said to create a situation of segregation and to be in breach of the principles of equality of treatment and equality of opportunity proclaimed by many international instruments. As the Committee on the Elimination of Racial Discrimination rightly pointed out in its 1983 annual report, establishing two systems of education may be understandable, but “might in time lead to the practice of discrimination among different strata of the population” (A/38/18, para. 197). Equality does not necessarily mean that treatment must be identical in all circumstances. According to established international case law and universally accepted doctrine, differentiation is not discrimination if the purpose is to achieve a legitimate goal and if there is a proportional relationship between the means used and the goal to be achieved. Only differentiation which is not justified de facto is inadmissible, provided that the criteria used are not reasonable and objective. In some countries, ethnic groups themselves assert their right to be treated as a separate and independent sector of the nation State’s education system and claim that they are entitled to a distinct indigenous education.18