Theme 1: Theory of science

1. What does Russell mean by "sense data" and why does he introduce this notion?
   How we see the things around us is not necessarily the truth about how they really are. If different people look at the same item they will perceive it differently. This is because our sense-data is different. Sense-data is how we use our senses to scan the world around us. We can use our sight, smell, touch, hearing and taste to get an understanding about an object. The sense data is not to be confused with the truth about the object. I.e the color of the object might be hard to distinguish if the surface is shiny and therefor the perception might be false.
   
   
   
2. What is the meaning of the terms "proposition" and "statement of fact"? How does propositions and statement of facts differ from other kinds of verbal expressions?
   There are different ways of learning, one is by acquaintance and another is by description. When we describe something we use propositions or statement of facts. They explain the object with different degree of truth. The statement of fact is verified to be true whereas a proposition is a statement based on beliefs. The proposition is built up by an object and its properties. I.e. in the proposition: the apple is red and juicy. "The apple" is the object and "red and juicy is its properties.
   
   
   
3. In chapter 5 ("Knowledge by Acquaintance and Knowledge by Description") Russell introduces the notion "definite description". What does this notion mean?
   Knowledge by acquaintance is knowledge that we get from ourselves by our sense-data or from our minds. Knowledge by description is what we get from others. Russell talks about two kinds of knowledge by description. One is the ambiguous description of the form: a so and so. The other is the definite form: the so and so. Simply put a definite description is a phrase of the form the so and so.
   
   
   
4. In chapter 13 ("Knowledge, Error and Probable Opinion") and in chapter 14 ("The Limits of Philosophical Knowledge") Russell attacks traditional problems in theory of knowledge (epistemology). What are the main points in Russell's presentation?
   Russell begins to question what is true and what is false and do we ever know anything? What is knowing, is it that our beliefs are true? What if our beliefs are false and by coincidence and luck the appear to be true anyway is one weakness of stating that true beliefs are knowledge. Not even by deducting premises can we be sure that our beliefs are true because we do not know if the premises are true.
   
   According to Russell there is two ways of knowing a fact is by acquaintance or description (perception and by propositions) . These are also criticized. If someone reads something they think that they have gained new knowledge. The text might have been full of lies or it could have been interpreted in a misleading way by the reader and then the reader would have learned nothing.