Together with E.F.E. Douwes Dekker, he was a strong political proponent of association between Indo-Europeans and Indonesians in the colonial Dutch East Indies and early post-colonial Indonesia.
From pre-colonial times (16th, 17th and 18th centuries) up to the first century of formal colonisation of the Dutch East Indies (19th century) the Eurasian hybrid culture of Indo-Europeans was very closely related to the indigenous cultures of the Indies archipelago. Although Indos were part of the European legal class its’ lingua franca and much of its practices and beliefs were derived from its’ indigenous maternal lineage.
In the 20th century the assault on Indo culture in the Dutch East Indies to Westernise accelerated, rapidly enforcing a one-sided identification with Dutch culture rigorously imposed by the ruling colonial authorities. From their historic role as indispensable intermediaries and change agents, the Indos were increasingly reduced to a marginal position in colonial society.
Simultaneously the Dutch Ethical Policy created an educated indigenous elite increasingly voicing the idea of Indonesian national independence. For the relatively small Indo-European community (less than 0.5 of the total native population) this posed the challenge of positioning itself between the emerging forces of the Indonesian National Awakening and the repressive forces of the colonial power.
Throughout the Japanese occupation of the Dutch East Indies in World War II and the following Indonesian revolution the existing estrangement between the native Indo-European population and indigenous peoples only widened and intensified.
In the first half of the 20th century during both the Dutch and Japanese colonial period as well as the Indonesian revolution Dahler was one of the leading Indo-European figures voicing the idea of so called ‘Association’ (integration of the Indo-Europeans into the indigenous population).