A/HRC/4/29 page 18 Institutional aspects 55. Although many of the respondents advocate the promotion of models of inclusive education, most also believe that it is necessary to maintain special education systems for children with severe disabilities or for those who simply prefer special attention. Many countries opt for combined systems of regular and special education that include a variety of modalities: regular education with special classes; special education only for those with a specific disability (usually motor or multiple); and preschool or temporary special education, such as institutions that prepare children with disabilities for educational inclusion. 56. The theories of inclusion and integration appear to contradict one another, with a marked tendency towards the persistence of modalities of segregated education. The recognition of these modalities as a prerequisite for guaranteeing the effective exercise of the right to education of persons with disabilities is accompanied by calls for a number of radical changes in education systems. 57. In the past, the special education system tended to treat individuals uniformly where no uniformity existed, and to differentiate among individuals where no differentiation was necessary. This arrangement has remained more or less unchanged in the shift towards inclusive education. Even today, a population segment may be considered to have “special educational needs based on disability”, without taking into account the fact that the effects of inclusion, even when access to inclusion is widely available, are subject to change and vary enormously in terms of their duration and content. 58. Mention should be made of the situation of deaf people in such countries as Sweden or the United Kingdom where, according to the NGOs surveyed, access to bilingualism is considered to be a prerequisite for egalitarian education; or the situation of blind people in Switzerland, where initial support results in subsequent equal education opportunities. In both cases, the principles of compensation and differentiation applied cannot be considered discriminatory since they recognize principles and rights, such as access to the country’s sign language and to literacy training in certain conditions. In short, the inclusion approach does not mean overlooking the particular features of the groups comprising the “disabled” population. It does, however, mean that those particular features should not be viewed as negative or deficient according to criteria and discourse derived exclusively from the medical model. 59. Systems for, and experience in, evaluating the quality and relevance of the education of persons with disabilities (both in regular and in special education) are practically non-existent. The European countries are the only countries that implement strategies and policies for evaluating these practices. It is more common to find evaluations of the performance of learners with disabilities, but such evaluations are still in the early stages. 60. In many of the countries considered in this report, public debt and inadequate investment are factors that limit the attainment and expansion of the right to education of persons with disabilities. The lack of resources for education as a result of financial dependence and the privatization and commercialization of education are obstacles to the expansion of this right.