This study examined how students' position on social-scientific issues (SSIs) influenced their performance on attitude toward science, science conceptual and argumentation learning. It defined two positions adopted by students regarding SSIs: affirmative and oppositional. The interactions between student position and two learning environments -- online and face-to-face -- were explored. A total of 214 11th-grade students from an educational priority area participated in our quasi-experimental study. They were assigned to four groups based on the two variables, position and learning environment. An online argumentation program was developed with a number of functionalities, such as sentence templates, anonymity, and asynchronous discussion blocks, to support the construction of multiple and evidence-based arguments. The findings show that the two variables significantly influenced students' attitude toward science and science conceptual and argumentation learning. There were significant interactions between the two variables in conceptual learning and two categories of argument: warrant and qualifier. The simple main effect analysis showed that the student groups that advocated a position of environmental protection and participated in online argumentation performed best. The follow-up qualitative analysis revealed that their stronger ethical standpoint and richer learning resources facilitated their co-construction of knowledge arguments and reconciliation following dialogue conflicts.