Abstract

In the contemporary information age, critical thinking is a vital competency for navigating complex, dynamic knowledge environments. This study examines how Indonesian junior-high students deploy conjunctions in descriptive essays and how these micro-linguistic choices index dimensions of critical thinking. Ninety-six Grade-VIII students at SMP Negeri 1 Balikpapan wrote essays under standardized classroom conditions; after plagiarism (<30%) and length (>100 words) screening, eighty-three texts were analyzed. Using an iterative qualitative content analysis, conjunctions were coded as additive, adversative, causal, temporal, or conditional, and surrounding clausal units were mapped to ten critical-thinking categories. Inter-rater reliability on 20% of the corpus reached κ = 0.82. Information synthesis dominated (22.3%), followed by evaluation (16.0%) and cause-and-effect (14.9%); argument construction (9.6%), problem-solving (8.5%), exemplification (7.4%), analytical reasoning (6.4%), generalization (5.3%), aspirational expression (5.3%), and creativity (4.3%) comprised the remainder. To contextualize aggregate patterns, we report descriptive (non-inferential) subgroup summaries by writing proficiency (lower/medium/higher—27/28/28), which indicate monotonic increases in conjunction density and type–token ratio with proficiency. We interpret conjunction use as a candidate, context-sensitive indicator—a trace of cognitive organization—rather than a causal determinant, noting the limits of the single-site, observational design. Pedagogically, the findings support an integrated framework that embeds explicit attention to conjunctions within genre-based writing and reasoning scaffolds (e.g., criteria-based evaluation, counterargument routines, reflective dialogue). Future work should triangulate these indicators with psychometric measures (e.g., Cornell Critical Thinking Test), extend to multimodal/genre-comparative analyses, and pursue longitudinal or multi-site designs to test generalizability.