物证鉴定的核心问题是“同一认定”理论和物证的特征由定性向定量的转化问题。物证的特征是物证所具有的客观条件和个人的主观条件相结合的产物。个人的知识与实践经验是确定物证特征的主观条件。共性特征和异性特征同属于物证同一认定的评判特征。共性特征决定肯定判断的方向 ,异性特征决定否定判断的方向。物证同一认定具有相对性和矛盾对抗性一面 ,不能把同一认定机械地理解为绝对的“同一”。正确理解和把握同一认定准确率的含义 ,不仅加深了对同一认定理论的正确理解 ,而且树立了唯物辩证法对立统一的世界观 ,对实践工作具有指导意义 ,避免认定工作中存在的盲目性 ,减少错误现象的发生 The core issue of physical evidence accreditation is the question of the transformation from qualitative to quantitative of the theory of “same identity” and the feature of physical evidence. The characteristics of material evidence are the product of the combination of objective conditions owned by physical evidence and personal subjective conditions. Personal knowledge and practical experience are the subjective conditions for determining the characteristics of physical evidence. Common features and heterosexual features belong to the same characteristics of the same identification evidences. Common features determine the direction of positive judgments, the opposite sex determines the direction of negative judgments. The same identification of material evidence has the relativity and contradiction confrontational side, can not mechanically identify the same identification as an absolute “same.” Correctly understanding and grasping the meaning of the same recognition rate not only deepens the correct understanding of the same theory of identity, but also establishes the world view of opposites and unity of materialist dialectics, which is instructive to practical work, avoids blindness existing in the work, and reduces errors The occurrence of the phenomenon