Almost every website that talks about it says, “Inductive reasoning is a bottom up” approach while “deductive is a top down approach”.
Can anyone explain to me the THE DIFFERENCE? What makes these two forms of reasoning so different? Examples are always appreciated as well.
In: 121
I’m taking critical thinking in college right now and this post gave me anxiety because I’ve been struggling to understand the terms and material. I’m saving this post to help me. Goodluck OP, hopefully you grasp it better than I did.
Inductive: the sun has risen every day prior to today. Therefore, the sun is going to rise this morning.
Deductive: all suns rise. We have a sun. Therefore our sun will rise.
Lawyers use deductive reasoning to give advice. They start with the rule then figure out whether something is legal or not.
Scientists use inductive reasoning. They use the evidence of the experiments to determine the underlying rules of the universe.
In reasoning, there are three components: a rule, a cause, and an effect. For example:
> Rule: Every time it rains, the grass gets wet.
>
> Cause: It just rained.
>
> Effect: The grass is wet.
There are three types of reasoning: deductive, inductive, and adductive. Each of them is missing one of the three components, but uses the other two to predict the third.
**Deductive reasoning** lacks the effect. So, you would know:
> Every time it rains, the grass gets wet (rule). It just rained (cause).
>
> Therefore, I conclude the grass is wet (effect).
As long as the rule and cause are always accurate, the effect will also be accurate. This type of reasoning is the most solid.
**Inductive reasoning** lacks the rule. So, you would know:
> It just rained (cause). The grass is wet (effect).
>
> Therefore, I predict that when it rains, the grass gets wet (rule).
However, there could be exceptions to the general rule that aren’t captured in observation. For instance, the grass could sometimes be under a tarp, preventing it from getting wet when it rains. Only further observation will tell. This is the basis of experimental science (do a bunch of things and try to find out if there is a rule).
**Abductive reasoning** lacks the cause. So, you would know:
> When it rains, the grass gets wet (rule). The grass is wet (effect).
>
> Therefore, I predict that it just rained (cause).
However, there could be many other causes for the effect. For instance, maybe the lawn sprinkler was just on. This is the weakest form of reasoning (and ironically what Sherlock Holmes actually uses the most).
Basically, there are 3 types of logical reasoning: deductive, inductive and abductive. The difference lie in what you already know, and what you are trying to know.
So there’s an action, a rule, and a result. For example: a horse passes in my hallway (action), a horse’s feet make clopping noise (rule), I hear clopping (result)
Deductive is having the action and the rule and you are deducting the result. I know a horse’s feet make clopping sounds, so if a horse walks in my hallway, I deduce I will hear clopping
Inductive is having the action and the result, and interpreting the rule. I am hearing clopping and a horse is walking my hallway, therefore a walking horse makes clopping noise
Abductive is having the rule and result, and using it to guess the action. I hear clopping, I know horses make clopping sounds when walking: therefore a horse is in my hallway.
You can induce a reason by passing a conductive material through a reason field. Reason fields are naturally generated by ponder-rocks. The most efficient way of doing this is to spin copper wires surrounded by ponder-rocks. Thats a simplified description of an MG (mental generator) . Even the phone you’re reading this on has an MMG (micro mental generator).
Easy way of describing it: deductive reasoning is a sort of mathematical certainty. If all of the premises/evidence holds up, and the logical structure is valid, then the conclusion *must* be.
“All dogs are cute, Amelia is a dog, therefore Amelia is cute.”
It’s bulletproof. If the first two parts are true, the next one *has* to be.
Inductive reasoning on the other hand is based more on arguing a conclusion is more likely, or better supported. It doesn’t have the same level of ironclad logic, but is still useful if not necessary all the time in day to day life.
“Organization A’s members tend to agree that *this* product does a better job at managing my symptoms than *that* product, Organization A’s members are experts in this field, so they’re probably correct.”
That argument hasn’t strictly “proven” anything; even if both premises are true the conclusion could still be false because experts can be wrong about stuff. But, it’s not trying to prove anything definitively, just lay out that the evidence leans in one particular direction.
Bonus points, if you were to try and frame the logic of an inductive argument to made a deductive one, that’s the most common type of logical fallacy. Taking that last one and changing the conclusion to say “so they *must* be correct”, you would have changed it to a deductive argument, and committed the Appeal to Authority fallacy.
Deductive reasoning gets you to absolute truth’s and falsehoods. You get certainty from deduction. “All bachelors are unmarried men” is an absolute fact. You cant argue it. If you see a man who is unmarried, you can say with absolute certainty that that man is a bachelor. It’s simply something that proceeds logically from the definition.
The problem is that most stuff isn’t as certain as a definition. This is where inductive reasoning comes in. “The sun will rise tomorrow” is a thing we’ve seen happen on a consistent basis for all human history, but can we claim beyond *any doubt whatsoever* that it will rise tomorrow? Most people would but if you talk to philosophers they’ll tell you we are *overwhelmingly confident* the sun will rise, but that we don’t capital-K ‘***Know’.*** We can eliminate 99.9% of uncertainty, but can never eliminate 100%. There is always something we can come up with to doubt a conclusion (what if the world blows up? what if a wormhole opens and sucks our sun away? what if we wake up and realize our whole life, including the sun, was a simulation?).
Scientists perform inductive reasoning. They subtract uncertainty to get closer to knowledge. They chip away at what they do not know, and what they’re left with is closer to the truth, but there’s always something else that can be chipped. They can tell you what the truth *probably* is, and give you an insane level of detail into exactly how ‘probably true’ it is.
In a general sense, deductive reasoning is using all the evidence available to you to draw a conclusion (deducing). Inductive reasoning is making an assumption and then proving if that assumption is true then a more general case is also true. So deductive reasoning is using a large amount of information to prove that a specific thing is true, while inductive reasoning is using a small amount of specific information to prove that a more general thing is true.
In a mathematical sense, deductive reasoning is using pre-established theorems to prove something is true, which is the most direct route to a proof. Inductive reasoning is generally a iterative approach where you show that, assuming null assumption (n0) is true, that if the n+1 is also true, then n+2, n+3….n+k must also be true. So you’re showing that if a specific instance is true, then the generalization is true.
Latest Answers