1. History of Philosophy

2. Modern empiricism (John Locke, George Berkeley, David Hume) and its self-destruction. The beginnings of the Enlightenment: the role of reason, toleration and human rights.

3. Empiricism claims that experience is a source or the source of knowledge and/or it justifies knowledge as true or at least probable. Although empiricism is mostly a modern philosophical school, nevertheless it is a very old strand in philosophy. It had been a part of the Greek philosophical tradition, and under the influence of Aristotle it became a part of scholasticism. Empiricism was defined in a formula by scholastic philosophers in the following way: nihil in intellectu nisi prius in sensu (nothing in the intellect that was not previously in the senses). Experience is understood as the sensory contents of consciousness, i.e., what we see, hear, touch, smell and taste or as judgments (statements) expressing (reporting) what is observed by the senses and therefore assumed as true.

4. A priori knowledge - without or prior to experience (analytic propositions) A posteriori knowledge - based on experience (synthetic propositions). Empiricism denies any a priori knowledge. Rationalism holds that true knowledge is available by reason alone, and its fundamentals are innate (inborn), and therefore are a priori. In the early modern era ( 17th c.) a controversy between empiricism and rationalism had began, and ended in the 1780s, in Kant’s philosophy, and was resumed in a different way in the 19th and 20th c.

5. John Locke ( ), whose philosophy commenced the British modern philosophy of empiricism, claimed that there are no innate concepts and principles, and knowledge originates in experience. We get our ideas (as he called them) of sensations from our senses and ideas of reflections from our introspection or inner experience. Our mind when we are born is empty or like “white paper, void of all characters, without any ideas.”

6. As he put it in his Essay Concerning Human Understanding (1690): “Idea is the object of thinking. Every man being conscious to himself that he thinks; and that which his mind is applied about whilst thinking being the ideas that are there, it is past doubt that men have in their minds several ideas,- such as are those expressed by the words whiteness, hardness, sweetness, thinking, motion, man, elephant, army, drunkenness /…/”

7. “All ideas come from sensation or reflection
“All ideas come from sensation or reflection. Let us then suppose the mind to be, as we say, white paper, void of all characters, without any ideas: - How comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? Whence has it all the materials of reason and knowledge? To this I answer, in one word, from EXPERIENCE. In that all our knowledge is founded; and from that it ultimately derives itself. Our observation employed either, about external sensible objects, or about the internal operations of our minds perceived and reflected on by ourselves, is that which supplies our understandings with all the materials of thinking. These two are the fountains of knowledge, from whence all the ideas we have, or can naturally have, do spring.”

8. Locke argued that we don’t know directly material objects, which exist independently of us, and following Democritus, claimed that at least some ideas represent adequately qualities of these objects (the so called primary qualities). Other ideas are merely responses of our senses and minds to unknown qualities (secondary qualities). Thus we can claim that objects are heavy or round, but not necessarily that they are sweet or sour, because sometimes they are such when we taste them and sometimes they are not.

9. George Berkeley ( ), the author of A Treatise Concerning the Principles of Human Knowledge, wherein the chief causes of error and difficulty in the sciences, with the grounds of scepticism, atheism, and irreligion, are inquired into (1710, 2nd edition 1734), was a more radical empiricist than Locke. He claimed that men are not able to know material objects in any way and they can only know their ideas of sensations which form different and incompatible objects of particular senses: visual, audible, tactile, olfactory and gustatory objects (the two latter ones can be also called organoleptic objects).

10. “By Touch I perceive, for Example, Hard and Soft, Heat and Cold, Motion and Resistance, and of all these more and less either as to Quantity or Degree. Smelling furnishes me with Odors; the Palate with Tastes, and Hearing conveys Sounds to the Mind in all their variety of Tone and Composition. And as several of these are observed to accompany each other, they come to be marked by one Name, and so to be reputed as one Thing. Thus, for Example, a certain Colour, Taste, Smell, Figure and Consistence having been observed to go together, are accounted one distinct Thing, signified by the Name Apple. Other collections of Ideas constitute a Stone, a Tree, a Book, and the like sensible Things; which, as they are pleasing or disagreeable, excite the Passions of Love, Hatred, Joy, Grief, and so forth.”

11. “/…/ [T]hat the various Sensations or Ideas imprinted on the Sense, however blended or combined together (that is, whatever Objects they compose) cannot exist otherwise than in a Mind perceiving them. I think an intuitive Knowledge may be obtained of this, by any one that shall attend to what is meant by the Term Exist when applied to sensible Things. The Table I write on, I say, exists, that is, I see and feel it; and if I were out of my Study I should say it existed, meaning thereby that if I was in my Study I might perceive it, or that some other Spirit actually does perceive it.

12. There was an Odor, that is, it was smelled; There was a Sound, that is to say, it was heard; a Colour or Figure, and it was perceived by Sight or Touch. This is all that I can understand by these and the like Expressions. For as to what is said of the absolute Existence of unthinking Things without any relation to their being perceived, that seems perfectly unintelligible. Their Esse is Percipi, nor is it possible they should have any Existence, out of the Minds or thinking Things which perceive them.”

13. He put his theory into a nutshell by saying that the existence of objects is their being perceived (their Esse is Percipi). Why such an odd theory? Berkeley’s aim was to prove the non-existence of material objects for theological reasons, but he was also a radical empiricist, who wanted to undermine traditional rationalist metaphysics as an unjustified bunch of statements. Only these statements of existence of sth may be accepted, which are based on experience. The existence of material objects cannot be justified by experience, because they are not sensed. We do sense only our sensory ideas.

14. David Hume ( ), the author of A Treatise of Human Nature ( ) not only argued that it is impossible to infer inductively universally valid propositions, but following Locke and Berkeley, he also claimed that our knowledge is based on perceptions: sensory impressions and their “copies”, i.e., ideas, and habits of mind. Why do we think that there is a causal link between A events and B events? Not because there is a necessary connection between them or a direct action of A’s on B’s as rationalists claimed, but because after multiple recurrence of B’s after A’s we habitually expect B’s to follow A’s.

15. “The idea of necessity arises from some impression
“The idea of necessity arises from some impression. /…/ necessity is something, that exists in the mind, not in objects; nor -is it possible for us ever to form the most distant idea of it, considered as a quality in bodies. Either we have no idea of necessity, or necessity is nothing but that determination of the thought to pass from causes to effects, and from effects to causes, according to their experienced union.” Non-empirical knowledge is formal (without empirical content), i.e. of “relations of ideas” (mathematics and logic).

16. Hume’s Fork matters of fact (empirical) propositions
relations of ideas (nonemiprical)

17. Three principles of association:
resemblance
contiguity in time and place
causation

18. Hume’s Law or Hume’s Guillotine
”In every system of morality, which I have hitherto met with, I have always remarked, that the author proceeds for some time in the ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surprised to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is however, of the last consequence.

19. For as this ought, or ought not, expresses some new relation or affirmation, 'tis necessary that it should be observed and explained; and at the same time that a reason should be given, for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it. But as authors do not commonly use this precaution, I shall presume to recommend it to the readers; and am persuaded, that this small attention would subvert all the vulgar systems of morality, and let us see, that the distinction of vice and virtue is not founded merely on the relations of objects, nor is perceived by reason.”
(A Treatise of Human Nature)

20. The derivation of ’ought’ from ’is’ is impossible or, in a weaker sense, should be avoided. IS -X-> OUGHT