1. Introduction

This chapter introduces the importance of critical thinking in writing and highlights the lack of empirical studies and specific instructional methods in previous research. It also emphasizes the need to focus on non-English majors' critical thinking abilities in writing.

2. Critical Thinking Ability

This chapter discussed the definition and skills of critical thinking. Critical thinking is defined as purposeful, self-regulatory judgment, involving interpretation, analysis, evaluation, and inference. It is emphasized by two influential definitions, as well as other scholars. The most famous models of critical thinking skills are proposed by Delphi Panel, Richard Paul and Wen Qiufang, which include cognitive skills and affective dispositions. Critical thinking ability is essential for writing, as it involves analysis, inference, and evaluation, as well as question, presupposition, argument, judgment, and logic.

3. Pragmatic Supposition

This chapter introduces the definition and characteristics of pragmatic presupposition, as well as its discourse functions. It also explores the roles of pragmatic presupposition in critical thinking ability of writing, and how it can provide a theoretical basis and practical instruction for the development of critical thinking ability in language teaching. The chapter highlights the importance of presupposition in the development of critical thinking ability in non-English majors’ writing.

4. Research Methodology

The research methodology chapter addresses specific research questions and provides details on the subjects, procedures, instruments, teaching and learning materials, instructions, and data collection and analysis. The subjects are 126 non-English major freshmen from a university in Shandong Province, with 68 in the experimental group and 60 in the control group. The experiment lasts for 14 weeks and uses the Ennis-Weir Critical Thinking Essay Test to measure critical thinking ability. The instruction for the experimental group focuses on critical writing from the perspective of pragmatic presupposition. Data collection and analysis involve sorting and analyzing all the data using SPSS 25.0, with calculations and tests conducted to assess significant differences between groups and within groups.

5. Results and Implications

5.1 The test results show that most college non-English majors lack critical thinking ability of writing. The biggest problem is that many subjects give incorrect judgments and are unable to provide proper reasons. The subjects' lack of critical thinking ability can be attributed to their weak English foundation and the neglect of developing critical thinking at the high school level.

5.2 Many writing exercises showcased unconvincing arguments, repetitive and lengthy descriptions, digression, and illogical or incoherent structures. These problems were attributed to the lack of critical thinking ability among the subjects.

5.3 Results of the writing tests between the experimental and control groups suggest that instruction from the perspective of pragmatic presupposition can help improve writing achievements. The improvements are not only reflected in writing scores, but also in the structures and contents of writing. The critical thinking ability used in the process of writing also demonstrated some obvious changes.

6. Conclusion

The non-English majors lack critical thinking ability, impacting their writing performance. The instruction led to improvements in writing structure and content. Teaching from the perspective of pragmatic presupposition may improve critical thinking in writing. Future studies should consider larger, more general samples and a longer study duration.