Posteriori knowledge, or empirical knowledge is propositional knowledge obtained by experience or sensorial information. Posteriori knowledge is a contrast to priori knowledge, which is knowledge that is gained through the apprehension of innate ideas, intuition or pure reason. Debate has focused on analyzing the nature of knowledge and how it relates to similar notions such as truth, belief, and justification. It also deals with the means of production of knowledge, as well as skepticism about different knowledge claims. ‘The traditional analysis of empirical knowledge states that you know that P if and only if you have empirically justified true belief that P.’ 
You don’t know why or have any idea of why reaction A follows situation B but you have seen it happen so many times that you know that is what is going to happen. I know how to drive a car in so far as I know that I use the accelerator to go and brake to stop and use the steering wheel to manoeuvre. I can get from A to B. In that respect I know how it functions in practice, but have little knowledge how cars actually work. Is it important to have knowledge of how things work? A person who knows how a car works doesn’t automatically know how to drive or may not be a better driver because of his particular knowledge. Many people and animals live quite a happy existence oblivious to knowledge or complicated thought process. I have gained knowledge over the last eighteen years without knowing about empirical knowledge.
The notion of innate ideas proposes that certain knowledge is present from birth. Empiricists would not want to deny that “all bachelors are unmarried” is a truth independent of experience, however they would deny that such a truth could be innate. For empiricists, the mind is a “blank slate”, Tabula Rasa. They believe that when we learn or experience things, it is as if the mind is being written on. Rationalists believe that the mind is similar to a computer, in which the hardware already has some functions, innate ideas, before the software, specific knowledge is loaded onto it.
John Locke believed that our experiences provided us with what he termed simple and complex ideas. A fine example of a simple idea may include the redness of a rose. We thereafter use these ideas in order to understand the world. An example Locke gives, is If someone burnt their hand on a flame but also on a extremely cold piece of ice, then one would form the conclusion that it is not heat that is responsible for the burns, but the difference in temperature. Thus, Locke thinks that the simple sensations and experiences for the basis for more abstract ideas.
Locke believed that knowledge could be of certain types depending on how ideas could be compared. Locke considered that the idea of black could be contrasted with that of white; and other ideas which share a common source, such as light and fire, which often go together. These ways of building up information, Locke thought are the main means by which we turn simple ideas into complex ones. Locke considered that there are three main types of knowledge. Intuitive, Demonstrative and Sensitive. Intuitive knowledge, “black is not white” is the most certain form of knowledge because it is the most difficult to doubt, and Locke argues that they are so obvious that we except them intuitively, as a priori. Demonstrative knowledge is when we begin to put simple ideas together and form complex ones, demonstrating something. Comparing the heat of the sun to the heat of a fire, one would be able to demonstrate that they are both made of similar substances. Locke argues that this form of knowledge is posteriori. Sensitive knowledge, Locke argues, is the most uncertain because it relies merely on the evidence of senses. If I look to see how many chairs there are in another room, I am relying on sensitive knowledge, which although considered a posteriori, can easily be mistaken
Rationalists argue by asking the question, that if one was to reject the idea that all of our knowledge comes from rational principles, how could we tell which of our perceptions are real or true? Locke’s answer to this lies in the existence of primary and secondary qualities that an object has. Applying this theory to a table, Locke considers the table’s primary qualities to be its size and shape, whereas the table’s secondary qualities are produced by powers in the object itself, which act on our senses to produce sensations and impressions. The colour, taste, and temperature of the table are all examples of a table’s secondary qualities.
George Berkeley pointed out that if all we ever see are primary or secondary qualities, how do we know that substance really exists? Berkley believed that there may be no such thing are matter, a view called Idealism. Berkley thought that Locke and other philosophers had potentially opened the door to atheism and scepticism by this view of knowledge. Berkley attempted to show that rather than sensations of objects arising from powers in the object itself, the experiences were actually in the perceiver. Berkley argues that the object does not need to possess any powers with which it produces effects on our senses, because the object does not exist apart from our perception of it. Berkley adopts the sceptical argument that we do not see objects as they really are. Berkley’s main argument was intended to show that it is possible for something to exist without being perceived. Berkley argues that it we cannot imagine what the perception of something must be like, we cannot really say that it exists. Berkley uses the idea to attack the notion of substance or matter, for if all the qualities that we ascribe to it are either primary or secondary qualities, can we actually say that the substance itself exists?
David Hume disagreed with such philosophers as Descartes that the mind contained innate ideas. He also disagreed with the idea that we could be certain about anything outside our experience or the true nature of the world. Hume divided knowledge into what he termed “relations of ideas” and “matters of fact”. Relations of ideas are analytic truths or priori statements that we cannot conceive of being otherwise, such as the statement “2 + 2 = 4” and “All bachelors are unmarried”. Matters of fact, however can be falsified. The statement “The sun will rise tomorrow” is extremely likely, however it is not impossible that it will not.
considered the answer to this is to suggest the existence of what he calls primary and secondary qualities. Hume argues that all our knowledge of cause and effect came through habit. So, for instance, if we see the Sun rise it is not because it corresponds to some eternal and unchangeable law, but because we have seen it rise countless times – what he terms, “constant conjunction”. Therefore, the more we have experienced things, the more certain they will be.
Theoretical and practical knowledge and understanding and experience are different types of knowledge. I think there is an important distinction between “knowing that” and “knowing how”. People knew that things fell down long before they “knew why” or there was an explanation of gravitation. Such knowledge was empirical. Most assumed knowledge or studies of things are known as theories. – Peoples ideas or take on things. Theory of evolution. Theory of relativity. Over time opinions are developed, they can be tested and become theories. Some theories become more certain and may become factual, but some remain doubtful or perceptions can alter, new light comes to ground that changes ones knowledge. Once it was thought that the earth was flat, and people could fall of the edge.
Edmund Gettier called into question the theory of knowledge and the traditional definition of knowledge. Gettier’s argument is that there are situations in which one’s belief may be justified and true, yet fail to count as knowledge. He contended that while justified belief in a true proposition is necessary for that proposition to be known, it is not sufficient. According to Gettier, there are certain circumstances in which one does not have knowledge, even when all of the above conditions are met. Gettier proposed two thought experiments, which have come to be known as “Gettier cases,” as counter examples to the classical account of knowledge. He argued it is possible to arrive at an assumption based on belief which is deemed justified, but happens to be true only by chance, because the outcome was predicted for the wrong reason and so can’t be classed to be knowledge.
Responses to Gettier have been varied. Usually, they have involved substantive attempts to provide a definition of knowledge different from the classical one, either by redefining knowledge as justified true belief with some additional fourth condition, or as something else altogether.
We are left a legacy of knowledge from those who have lived before us and thus accumulated knowledge over thousands of years. It would be impossible for any individual to experience all this knowledge ‘first hand’. I have learned that there is a difference between “knowing that” (facts and information) and “knowing how” (the ability to do something), because it is one thing to know what empirical knowledge is, but another to have the ability to convey this in an essay, to show this knowledge.
In conclusion from continued observation things should become obvious. For things to become factual I guess they should be observed by several people and the same conclusion be deducted. Should one believe or trust other people’s conclusion of events? Or is it necessary to observe and test theories oneself in order to form ones own
conclusions and gain knowledge. I’m not really sure there is one conclusion to be made. It is possible to judge some