Theme 1: Theory of Science

Bertrand Russell – The Problems of Philosophy

1. What does Russell mean by "sense data" and why does he introduce this notion?
When we catch sight of a physical object our mind makes up a sensation of what it is. Russell explains that it is through our senses (sight, touch, hearing, taste, smell) that we interpret an object receiving the sense-data of it. We are not immediately aware of the physical object, but rather the sense-data of it. The sense-data differ among people depending on how our mind creates an understanding of the object, where prior knowledge, experiences and physical laws are taken into account. Therefore, people often experiences one and the same object differently. I believe that Russell introduces this notion to highlight two aspects that are important in the field of communication. At first, there are different stages of knowing. What you see, at a first glance, is merely a rough interpretation of what your senses register, which is often changed at a closer look. Secondly, everybody has their own perception of the sense-data. Hence there are of importance to understand that there is no “right or wrong”, but all people perceive things differently (according to their own point of view).

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?
Propositions about objects are statements in our minds, which are known to us by description. We are not acquainted with the object in the proposition and therefore not aware of the facts about it. However, a proposition must be completely composed of constituents that we are acquainted with. That is, we must have facts about things regarding the object in the proposition. In some cases we have knowledge by description of things which we have never experienced, so called a proposition with “a priori knowledge". A statement of fact is something experienced in acquaintance, which has led to a belief. When an object or a fact of the statement corresponds with our beliefs it is considered as “true”. Unlike other verbal expressions, propositions and statements of facts are based on knowledge, and not only prior experience, rumors etc.

3. In chapter 5 ("Knowledge by Acquaintance and Knowledge by Description") Russell introduces the notion "definite description". What does this notion mean?
When Russel introduces the term “description” he illustrates a difference between “ambiguous description” and “definite description”. An “ambiguous description” is on the form “a ‘so-and-so’” where not a particular object or a specific person is pointed out, but it exists many of the same kind. In contrast, Russell defines “definite descriptions” as words or sentences on the form “the ‘so-and-so’”, which describes a unique object or person. The knowledge of this unique object or person does not come from immediate acquaintance, but rather from the acquaintance with things regarding these. We receive knowledge from acquaintance by our memory, sense-data, or through introspection with our sense-data.

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 argues whether there is something that can be entitled “true knowledge” or not. According to Russell, knowledge is not an exact conception and the scientific knowledge does not differ that much from philosophical knowledge. The main thing that divides the two is criticism. He puts to light that true belief cannot be called knowledge if it is deduced by a fallacious process of reasoning, even if the premisses from which it is deduced are true. In general, knowledge is probable opinions proved theoretically as we are not acquainted with objects or facts personally. Further, we do not know the universal relations between all included facts, which is a condition to totally receive knowledge. An opinion isolated from others does not make something true knowledge, but many matching opinions make knowledge more probable. Russell also addresses that we by no means easily can discover criterion for intuitive beliefs, which leads him to a conclusion that all our knowledge of truths is infected with some degree of doubt, and a theory which ignores this fact would be plainly wrong.