Deduction and Induction Essay
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The Difference between Deduction and Induction Essay
Logical thinking is based on making assumptions, testing them and drawing reasonable conclusions from the results. Two of the main methods of reasoning are deduction and induction.
Both of them are based on drawing conclusions between different cases. The difference between them, as described below, is their “directions”, or their logical approaches.
Deduction is the way to drag a rule from the general case to the private one. It is generally based on prior knowledge or theories and therefore does not add to the base of knowledge rather than using existing information to explain a phenomenon that it relevant to other occurrences which have the same explanation. Therefore, the deductive hypothesis will be “if X and Y are similar, and X happens because of Z, then Y is also a result of Z”. Since deduction goes from proven rules to check a hypothesis through observations in order to provide reasoning behind a particular case, it is called a “top-down” approach.
Induction is the complete opposite way of reasoning. Here, a “bottom-up” approach is used; a single observation or finding is used to characterise the general group. Since not of the elements are to be seen, inductive reasoning is somewhat weak in terms of validity, and therefore is rejected in the science of mathematics.
To illustrate this point, let us imagine a bag full of colourful balls. After taking out 10 balls from the bag, we observe that all of them were red and therefore conclude that the bag is full with only red balls. Doing so, we made an inductive assumption regarding the colour of all the balls on the bag. However, no one can say that the 11th ball cannot be blue; hence, our observation is not valid regarding the rest of the balls in the bag.
Unlike deductive reasoning, which is based on testing hypothesis, inductive reasoning is much more open in nature, since its direction is infinite. For this reason, many of history’s great discoveries were based on inductions.
When formulating his theory of evolution, Darwin used inductive reasoning since his theory is based on observations he made and due to the fact that there was no previous teaching of evolution from which he could deductively come up with other ideas. In other words, he observed several kinds of animals as evolved from each other and changed to meet the environmental challenges (as it was the case with Galapagos finches) he concluded that all finches or even all animals evolve from each other to meet the needs of changing environment which provides survival only for the fittest. With that conclusion in mind, he would deductively tie all behavior of all animals to their desire to fit into the environment and survive.
Newton also used inductive reasoning to make his conclusions about the law of gravity. His observations on particular occurrences (e.g., the apple falling down the tree) were the only basis he had for assuming rules of attraction between planets and the bodies on their proximity.
Nevertheless, we should not assume that all deductions are true and all inductions are false. A deduction is based on its presumptions, namely the possible similarity between cases. As critical thinkers, we must pay special attention to these assumptions. If one of them appears to be wrong, than the whole deduction is necessarily wrong. On the contrary, if an hypothesis based on deductive reasoning is proven as false, one should not draw an inductive claim that the basic assumptions were also wrong, except the assumption of premises, meaning the hypothesis that binds the specific case to a certain group.
Despite the differences between them, deductive and inductive reasoning both share a similar pattern. They both move between the general and the individual, but on different directions. Therefore, every deduction can be explained by an induction and the other way around. In addition, they support each other, for example by using inductive methods to construct deductive premises. This pattern is an essential building brick in all sciences; using statements like “if X than Y” or identifying a link between phenomenon that appear different represents a complex manner of thinking, opposite to the world of predetermined schemes and pigeonholes.