PP110 Lecture : lecture 1.docx
Document Summary
Every claim in philosophy must be justified (at least stated to be self-evident) Set of premises aimed to support a particular conclusion. To say one claim, r, is deduced from some others, p and q, is to say that if we hold p and q to be true, that is, one is rationally obliged to accept, r, as true. Deduction is all or nothing: if premises are true, no choice but to accept conclusion is true. Argument is valid when its conclusion must follow from its premises. Conclusion of valid argument doesn"t have to be true. Eiffel tower is in london or beijing. Rationally obliged to believe the conclusion based on the validity of the argument but premise (2) is invalid which results in invalid conclusion. Henry is a martian, than he is under 1m tall. Valid conclusion due to validity of premises. Holmes finds premise (1) to be true due to consistent observation of mark on cyclist"s shoes.
