To understand syllogisms, you need to familiarize yourself with several terms often used when discussing formal logic. At the most basic level, a syllogism is the simplest sequence of a combination of logical premises that lead to a conclusion. A premise is a proposition that is used as evidence in an argument. A conclusion is asserted by the logical result of an argument based on the relationship of the stated premises. Consider the conclusion of a syllogism to be the "thesis" of an argument. In other words, the conclusion is the point proven by the premises. Recall that a syllogism includes a major premise, a minor premise, and a conclusion. Jumping into an example: "All humans are mortal" might function as a major premise, and would stand as a generally accepted fact. "David Foster Wallace is a human" might follow as a minor premise. Notice that the minor premise is more specific, and immediately relates to the major premise. If each of the prior statements are considered valid, the logical conclusion would be "David Foster Wallace is mortal." Both the minor and major premises of a syllogism must have one term in common with the conclusion. The term that is in both the major premise and the conclusion is the major term, which forms the predicate of the conclusion in other words, it states something about the subject of the conclusion. The term shared by the minor premise and the conclusion is the minor term, which will be the subject of the conclusion. Consider the example: "All birds are animals. Turkey vultures are bird. All turkey vultures are animals." Here, "animal" is the major term, as it is in both the major premise and is the predicate of the conclusion. "Turkey vulture" is the minor term, as it is in the minor premise and is the subject of the conclusion. Notice that there is also a categorical term shared by the two premises, in this case "bird." This is called the middle term, and is of immense importance in determining the figure of the syllogism, which is addressed in a later step. If you're preparing for a logical reasoning test, or simply want to better understand syllogisms in general, note that most syllogism you will encounter will be categorical. This means that they will rely on reasoning akin to: "If ____ are/are not [members of a category], then ____ are/are not [also members of that category/a different category]" Another way to think of the logical sequence employed by categorical syllogisms is that they all employ the logical sequence of "Some/all/no _____ is/isn't ______." There are four different types of propositions that can be made by each of the three parts of a syllogism. Think of how they differ in terms of how they each distribute or don't distribute any categorical term. Consider a categorical terms to be "distributed" only if all individual members of that category are accounted for in the term. For example, in the premise "all men are mortal", the term "men" is distributed, as every member belonging to that category is accounted for in this case, as mortal. Note how each of the four different types of propositions distributes (or does not distribute) the terms: In "All X are Y" propositions, the subject (X) is distributed. In "No X are Y" propositions, both the subject (X) and the predicate (Y) are distributed. In "Some X are Y" propositions, neither the subject nor the predicate are distributed. In "Some X are not Y" propositions, the predicate (Y) is distributed. Enthymemes, aside from having another really hard to pronounce name, are simply compressed syllogisms. Another way to think of an enthymeme is as a one-sentence syllogism, which may help you recognize both how and why syllogisms are a convenient reasoning device. In specific terms, enthymemes disregard the major premise and combine the minor premise with the conclusion. For instance, consider the syllogism: "All dogs are canine. Lola is a dog. Lola is a canine." The enthymeme of this same logical sequence would be: "Lola is a canine because she's a dog." Another example of an enthymeme is "David Foster Wallace is mortal because he is human."

Summary: Recognize how a syllogism makes an argument. Determine the three parts of a syllogism. Determine the minor and major terms. Look for categorical terms. Understand the distribution of terms in a syllogism. Identify an enthymeme.

Be sure to do this to avoid short-circuiting the electrical system during the installation, which could lead to fire or physical harm for you. For instructions on disconnecting the battery, see How to Disconnect a Car Battery. Be careful to remove all screws before trying to pry off the trim or you may break it. For some cars, you may need to remove several pieces of plastic trim, usually working from the bottom up. If you need to remove trim that includes any knobs or drawers, remove them before trying to pry off the trim. Use your hands or a pry tool to pry off each piece of trim. Pry tools are specifically for this purpose and will not damage the trim pieces. If you need to remove any components before being able to access the stereo, do so. Disconnect components that are wired to the car. Take a picture of how each is wired for later reference. Different cars may have varying elements securing the stereo in place. If the stereo is held in place by screws or nuts, loosen them with the appropriate tool (screwdriver or nutdriver, respectively). If the stereo isn't held in place by screws or nuts, you'll need to use a radio-removal key. This tool is commonly necessary in Ford vehicles. Radio-removal keys (sometimes also referred to as radio-removal tools) will typically either be in an elongated horseshoe shape or will have a circular shape at one end and a notched shaft at the other. They're available at most auto-parts stores. Insert the keys into the two small slots in the face of the stereo. You will release a mechanism holding the stereo in place. Slide the radio-removal keys into each slot again until you feel the stereo loosen from in its housing. You should then be able to pull out the stereo relatively easily. You may want to use needle-nose pliers to grip the edge of the stereo and help you pull it out. Pull it gently, and if the stereo doesn't come out easily, double check that you haven't missed any components that may be holding it in place. This is an important step because the photo will serve as a reference later when you're wiring in the new stereo. You'll see a series of wires connected to the back of the stereo, and you'll need to disconnect each of them. First unplug the antenna wire, which will typically be a thicker wire plugged in separately from the rest. Once it's unplugged, you should be able to move the stereo around more freely. Next unplug the each of the wire harness connectors. There will typically be several of these and you can recognize them because a series of wires will feed into each one. The plastic piece into which the wires are fed should have either a tab or a button you can push, which will release the harness.
Summary: Set the parking brake and disconnect the negative cable from your car battery. Unscrew any screws that are securing the trim in place. Remove the trim. Pull out any necessary components. Loosen the stereo. Pull the stereo out of the panel. Take a picture of how the stereo is wired. Unplug the stereo connections.