 The term logic applies to human reasoning, where it defines thinking according to a set of consistent and coherent rules and the domain of philosophy that studies these principles of correct reasoning. Likewise, the term may be applied in a more generalized sense, where a logic is any integrated and ordered set of relationships between entities that is intelligible. For example, we might say there is a certain logic to the motion of rush hour traffic, or that there is a certain logic to the movement of the earth around the sun. This is the meaning of the word we're using when we say that politics has no logic, or can you see the logic in a cup that holds no liquid? And it's this generalized sense of the term logic that we'll be talking about in this video. A logic is the system or set of principles underlying the arrangement and behavior of elements in a system. All ordered systems have a set of relationships between their parts that defines the whole system and how its parts behave. This set of interrelationships that defines the parts is the logic of the system. For example, there is a logic to the behavior of a horse, because it is defined and governed by a set of interrelationships between its elements and its connections with its broader environments. A horse will exhibit certain behavior as a product of this set of interrelationships. If we give the horse some hay and some meat, it will eat the hay, not the meat. This behavior to the horse is governed by a logical set of relationships between its parts and its environment, and this we would say is the logic governing the horse's behavior. In this case, the fact that its digestive system is designed to process hay, not meat. Logic then refers to the interrelationships between things, the fact that there is some order to these interconnections, and through them the behavior and features of the parts are defined by the whole organization and the logic of its relationships. The logic to a shop and how to run a shop is governed by the many things that it is interconnected with, customers, suppliers, local and global economy etc. When the shop owner decreases the price of some product, she does this according to some set of logical relationships with the other elements, because she believes it will attract more customers into the shop, or because they've just received a discount delivery or they're overstocked etc. The shop owner is acting logically because she is acting in accordance with the logic of being a shop owner, the set of interrelationships with other things that this entails. Likewise, all systems have a logic that governs their behavior, and it is through that set of interrelationships that the parts are defined. For example, we cannot understand what a mother is without understanding what a child is. It is the logic between them that defines each and creates a dynamic that drives their behavior. To properly understand what parenting is, one has to in fact understand a whole mirrored of things, such as at least the idea of a child, the idea of birth, the idea of youth, of responsibility, nurturing etc. One has to understand all of these things to understand the idea of being a mother, because the mother's state and behavior are defined by her interrelationship with all these other factors and the logical set of relationships between them. The idea that there is a logic behind things is the central premise of critical thinking and science in general. Science presumes that things and events in the universe occur in inconstant and intelligent patterns that are comprehensible through careful and systematic study. Scientists believe that through the use of reason and with the aid of instruments, people can discover patterns in all of nature. The fundamental assumption of all of science is that the world around us is logical in some way. That means that there is some pattern to the relationship between things and events that can be understood intelligibly and this forms the logic of a particular domain. We can say then that it is this logic that researchers within a particular domain are trying to use reason to discover. In this sense, all domains of study and science represent a particular logic. A subject then is a set of ideas that are interrelated in a logical way to try and capture the logic behind some system in the world. Things have meaning and definition as part of a broader system of logic that defines them. To understand what something means, one has to understand the logic governing the broader system it is a part of. In reasoning, one tries to figure out this logic of things because in a system that exhibits any degree of complexity, its dynamics or logic will not be manifest. We will simply see events, possibly some associations will be manifest but not all and it requires systematic thinking in the form of reasoning to derive the underlining logic to those systems. One can say then that learning a body of content such as an academic discipline is equivalent to learning to think within that discipline. Hence to learn biology, one has to learn to think biologically. To learn sociology, one has to learn to think sociologically. Biologists are trying to construct the logic of living things. Physicists are trying to figure out the logic of physical systems. Sociologists are trying to understand the logic behind social systems etc. It is in this sense of logic that the idea of objective knowledge can have foundation. To have objective knowledge is to understand how something really works which is equivalent to understanding the logic of the system under consideration. Knowledge that is of value is knowledge that is objective which means that it is relevant within many frames of reference. It stays working under many different circumstances and this can only be achieved by understanding the deep logic to the system. A piece of knowledge that is only applicable under certain circumstances only applies to certain people or cultures is of less value than knowledge that is relevant to all situations. This more objective knowledge is a product of understanding the broader logic behind the system. With critical thinking, we're not doing philosophy in searching for deep metaphysical truths with the capital T. But like science, critical thinking is much more practical. It is a search for knowledge that works and stays relevant independent of place, time, society or culture. Critical thinking and science are standards and methods for a process of inquiry that will help us to develop objective knowledge, knowledge that works and has value independent of anyone's evaluation. It is by understanding the logic of photons that we can create lasers and any society anywhere on the planet can now create lasers. By understanding the logic of the human body we can cure diseases with the logic of energy conversion that is captured in the knowledge of thermodynamics. We can send rockets to the moon. But in order to understand this subjective knowledge it is required that our subjective conceptions are shaped to conform with the external logic of the systems we're considering and not the other way round. This has been achieved in the case of science through the application of objective standards and methods. And this is a central part of what critical thinking is about. It's about developing standards for our thinking so that we can reason effectively and thus derive the logic of things and create knowledge that is valuable.