If sand is to house, then assumptions are to products. Sand is the basic ingredient required to build a house. You can say it is readily available as a free gift of nature if you can take the effort to search for it and pack it otherwise you buy it. So also, is assumptions to building a product. Assumptions are the basic ideas/ presumptions we have about a thing, person, or entity. It is also free. People make assumptions daily. When you need more assumptions, you can choose to enquire and search for people to give you or you can choose to pay an agency to do the research work for you. Without sand you cannot build strong concrete for a house so also without assumptions you cannot find out and build the best product.
An assumption is something that you accept as true without question or proof.
People tend to make various types of assumptions about people, products, and things. For example, people might make the assumption that you’re a nerd if you wear glasses, even though that might not be true or people can make the assumption that a book is not great because the cover is not appealing which also might not be true.
However, as misleading as assumptions can be, they are also very important. Without assumptions, there is no starting point to grow your viewpoint from.
Take for example you want to build a product for young people to be able to get purchased products quicker and with cheaper logistics. You thought about this idea, and it is probably a pain point for you. Moving from solving your problem/pain point to building a solution for this problem so many can use it, you are making the assumption that young people actually need that solution. They might need it or they might not need it. This is the basis of assumptions.
There is a tendency to mix up assumptions with Facts.
You must always be able to identify all assumptions in a Proposed solution or product. Failure to identify them might lead you to build a product that you assumed people need but they do not. 90% of failed products are not necessarily because the products are not great in themselves but rather because there was no market/need for the product.
Whatever you cannot say for certainty with backup (data) that is true is an assumption. Even when you have researched and have heard people say they need it, that still holds a level of assumption as people do not usually do what they say. So, until they are able to pay for a product, they claim they need, it might just be all talk.
This is the reason why after identifying and listing out all the possible assumptions associated with your product, you need to confirm/validate this assumption by releasing a clickbait(Email claiming to provide a solution for example) at the very least or an MVP to know if people see something like what they claim to need, they will pursue it.
If you’re just starting out in Product Management, this is something you need to familiarize yourself with. Let me know in the comments if you find this helpful. Cheers.