•There are different types of knowledge: acquaintance, ability and propositional knowledge. Theories of knowledge discussed here are about propositional knowledge. •Knowledge is not the same as belief. Beliefs can be mistaken, but no-one can know what is false. •Knowledge is not the same as true belief, either. True beliefs may not be justified, but can be believed without evidence. To be knowledge, a belief must be justified. •Rationalism claims that we can have synthetic a priori knowledge of how things are outside the mind. •Empiricism denies this.
It claims that all a priori knowledge is only of analytic propositions. Do all ideas derive from sense experience? •Locke argues that the mind at birth is a ‘tabula rasa’ – there are no innate ideas, which Locke defines as ideas present in the mind from birth. •Locke argues that there is no truth that everyone, including idiots and children, assents to – so no truth is innate. •Rationalists define innate ideas as ideas (concepts or propositions) whose content can’t be gained from experience, but which are triggered by experience.
•Locke and Hume argue that all concepts are derived from sense experience, from impressions of sensation or reflection. •They claim that simple concepts are copies of impressions; complex concepts are created out of simple concepts by combining and abstracting them. •One argument for innate concepts is to challenge the empiricist to show how a particular complex or abstract concepts, for example, a physical object, is supposed to be derived from experience. If it cannot be, and it is used by children, then this is a reason to think it is innate.
Are all claims about what exists ultimately grounded in and justified by sense experience? •Hume argues that all a priori knowledge is of relations of ideas, and so analytic. All knowledge of synthetic propositions, matters of fact, is a posteriori. It depends either on present experience or causal inference, which relies on past experience. •Our knowledge of matters of fact that relies on induction can only be probably – never proven. •Some rationalists, for example, Descartes, try to show that we can use a priori intuition and deductive argument to demonstrate what exists.
•The core of the idea of rational intuition is that you can ‘see’ the truth of a claim just by thinking about it. •Descartes argues that sense experience on its own cannot establish what exists – how can we know that all sense experience is not a deception cause by an evil demon? •He argues that he cannot doubt his own existence, and that the mind can exist without the body. •Descartes argues for the existence of the physical world by first arguing for the existence of God. From God not being a deceiver, it follow that our sense experience in general can’t be completely mistaken – so they physical world exists.
Conceptual schemes and their philosophical implications •Thinkers who defend the idea of conceptual schemes often argue that there are two distinguishable elements to our experience – the data of the sense, and then the interpretation of these data by a set of concepts. •Some argue that human beings have formulated different conceptual scheme which are not translatable into each other. From the same sense experience, they form different views of the world. •Because we must use concepts to formulate truths, we can argue that truths are relative to conceptual schemes.
Or more accurately, some truths can only be stated in certain conceptual schemes and not others, and there is no one conceptual scheme which we can use to state all truths. Do all ideas derive from sense experience? II •One objection to the empiricist theory of the origin of concepts is that there are some complex concepts, for example, knowledge and beauty that cannot be analysed in terms of simpler concepts. •A second objection is that some simple ideas, for example, a particular shade of blue, don’t have to be derived from sense impressions.
Empiricists can respond in two ways: all ideas could be derived from sense experience’ or some ideas are exceptions to the rule that all ideas are derived from sense experience, but these exceptions are derived from ideas that are derived from sense experience. •Another objection is that it is not possible to derive any concepts from experience, because in order to form concepts, we must make judgements of similarity and difference to classify experiences. But we can only make these judgements if we already have the concepts.
•Defenders of innate ideas maintain that we innately have very specific capacities for forming particular ideas, and these ideas count as innate. •Suggestions for the origin of innate ideas include evolution, God, and a previous existence. Are all claims about what exists ultimately grounded in and justified by sense experience? II •Rationalists claim that we have synthetic a priori knowledge either innately or through rational intuition •Plato argues that many particular objects can have the same property, for example, beauty.
These properties can exist independently of the particular objects, as shown by the fact that is we destroy all beautiful things, we haven’t destroyed beauty. These properties are instances of the Forms. •Plato argues that innate concepts are our knowledge of the Forms, from a previous existence. Unless we had such innate memories, we wouldn’t be able to classify experience using concepts. •Descartes argues that he cannot doubt his existence. We can object that he cannot know he exists; only that thoughts exist. •Descartes also argues that the mind can exist without the body.
We can object that just because he can conceive that this is possible doesn’t show that this is possible. •Both these arguments and the objections use a priori reasoning. Hume objects that a priori reasoning can only establish analytic truths. •Nietzsche argues that reasoning is not, in fact, something independent that reveals the truth, but is grounded on assumptions about value. Metaphysical theories are the result of attempts to defend a particular way of understanding the world, one that rests on the false assumption that good and bad are opposites.
•The verification principle claims that a statement only has meaning if it is either analytic or empirically verifiable. However, the principle itself is neither analytic nor empirically verifiable. •Rationalists argue that mathematics is an example of synthetic a priori knowledge. Empiricists argue that mathematics is analytic. Is certainty confined to introspection and the tautological? •Descartes argues that what we can doubt is not certain enough to be knowledge.
However, we can argue that certainty and justification are not the same thing, and that while knowledge needs to be justified, we need an argument to show that it must be certain. •Certainty can refer to a subjective feeling, to a proposition being necessarily true or to the impossibility of doubting a proposition. •Empiricists claim that analytic truth is the only kind of necessary truth. Rationalists argue that there are synthetic a priori truths that are also necessary. •A necessary truth is certain.
Claims about mental state, based on introspection, may also be certain for the person whose mental states they are. •Whether any other claims are certain depend on whether there are necessary synthetic a priori truths. Conceptual schemes and their philosophical implications II •Kant argues that experience is of objects, and asks how it is possible for experience to be intelligible in this way, not a confused buzz. •He answers that what makes experience possible are certain concepts, which he calls categories. These categories together express the ‘pure thought of an object’.
•One such category is causality. This enables us to distinguish the temporal order of our perceptions from the temporal order of objects. •Kant argues that to talk of concepts interpreting sensation is misleading. Our sensory experience is always already conceptualised as experience of objects. •Two implications of Kant’s theory are that the structure of the everyday world of objects is defined by our a priori concepts; and that we cannot know anything about how reality is completely independent of how we think of it.