Key Arguments

• Locke connects probability to its function: 'Probability then, being to supply the defect of our knowledge and to guide us where that fails, is always conversant about propositions whereof we have no certainty, but only some inducements to receive them for true,' and then identifies its bases.
• He states succinctly: 'The grounds of it are, in short, these two following:— First, The conformity of anything with our own knowledge, observation, and experience. Secondly, The testimony of others, vouching their observation and experience.'
• He further analyzes testimony by listing six relevant considerations: 'I. The number. II. The integrity. III. The skill of the witnesses. IV. The design of the author, where it is a testimony out of a book cited. V. The consistency of the parts, and circumstances of the relation. VI. Contrary testimonies.'
• Through these distinctions he implies that probability is not a single homogeneous notion, but depends on complex factors relating both to the fit with what we already know and to the quality and context of others’ reports.

Source Quotes

4. The grounds of probability are two: conformity with our own experience, or the testimony of others’ experience. Probability then, being to supply the defect of our knowledge and to guide us where that fails, is always conversant about propositions whereof we have no certainty, but only some inducements to receive them for true.

The grounds of probability are two: conformity with our own experience, or the testimony of others’ experience. Probability then, being to supply the defect of our knowledge and to guide us where that fails, is always conversant about propositions whereof we have no certainty, but only some inducements to receive them for true. The grounds of it are, in short, these two following:— First, The conformity of anything with our own knowledge, observation, and experience.

Probability then, being to supply the defect of our knowledge and to guide us where that fails, is always conversant about propositions whereof we have no certainty, but only some inducements to receive them for true. The grounds of it are, in short, these two following:— First, The conformity of anything with our own knowledge, observation, and experience. Secondly, The testimony of others, vouching their observation and experience. In the testimony of others is to be considered: I.

Secondly, The testimony of others, vouching their observation and experience. In the testimony of others is to be considered: I. The number. II. The integrity. III. The skill of the witnesses. IV. The design of the author, where it is a testimony out of a book cited. V. The consistency of the parts, and circumstances of the relation. VI. Contrary testimonies. 5.

Key Concepts

• The grounds of probability are two: conformity with our own experience, or the testimony of others’ experience.
• Probability then, being to supply the defect of our knowledge and to guide us where that fails, is always conversant about propositions whereof we have no certainty, but only some inducements to receive them for true.
• The grounds of it are, in short, these two following:— First, The conformity of anything with our own knowledge, observation, and experience. Secondly, The testimony of others, vouching their observation and experience.
• In the testimony of others is to be considered: I. The number. II. The integrity. III. The skill of the witnesses. IV. The design of the author, where it is a testimony out of a book cited. V. The consistency of the parts, and circumstances of the relation. VI. Contrary testimonies.

Context

Book IV, Chapter XV, §4, where Locke classifies the fundamental epistemic bases of probability and unpacks the factors relevant to evaluating testimonial evidence.