If we are going to be able to think about anything at all, we have to start somewhere. Where do we start then, and why? If we do not know, then can we think anything at all (intelligibly)?
There appears to be no universal consent on any fact of existence; facts do not appear to speak for themselves, they must be interpreted, else everyone would agree and as already said they do not.
You have made mistakes before, why not again? How do you know that you are not making a mistake even now? Remember those things you felt so certain of, then a new fact came along and overturned everything you believed so strongly? What is to guarantee that there is no fact out there which you have not discovered and never will which would completely overturn everything you believe to be true?
We all know how fallible the senses are. They are easily affected by emotions, health, alcohol, distance, etc. The senses are often impaired. How do we know that our senses are keen enough to gather information that we need from the world? Dogs can hear things that humans cannot. How do we know that we even have enough senses to understand the world? There are animals with no eyes that appear to live happily everyday without a worry of what they are missing. What if we are missing important senses that we need to truly understand the world? How do we know that we are not?
Even if we have an entire world set out in our mind, how do we know that this is the way the world really is? That is, how do we know that our conceptual map matches the external world, or that there even is an external world? We cannot step outside of ourselves. How do we judge our cognitive or sensory tools?
Do we know anything at all?
There is an appeal to a higher standard, higher standard, higher standard, etc. This cannot go on indefinitely or else nothing is explained. There are some things we just have to believe before we ever begin to think. The Christian’s highest standard is God. There is no one else above God.
When God made a promise to Abraham, since He had no one greater by whom to swear, He swore by Himself.
Ultimately we believe in the God of Christian Scripture who has revealed Himself to us through our being made in His image, through the things that are made (not design arguments, just by virtue of the things which are made), and through Scripture. This is the thing that we as Christians believe from the very start. It comes down to faith in this.
The non-Christian will whine about this! She will not accept Christ as Lord of her thought, she will refuse to start from the same place that we do, with the same belief that we do. The problem is that what follows from her unbelief does not get her anywhere. For example, consider the laws of nature which she has faith in. Laws of nature are merely descriptions of the way that nature has been observed to behave. There is absolutely no guarantee that nature will continue to behave the same way in the future that it has in the past. Our unbelieving friend constantly acts on the idea that nature will continue to be the way it has been in the past, but without any reason at all for doing so. So she is without any ground for her belief in the consistency of the laws of nature, and she is without anything else since there are not many beliefs one can derive from laws of nature.
Meanwhile what follows from our belief in God and Scripture is that God has created our minds in such a way that we come to know Him, ourselves, and the world (because knowing ourselves and the world ultimately result in our knowing God better) and so the belief he has given us that the future will be like the past matches with the world so that His ends (of us knowing things) is accomplished. We also know that God is an orderly God and have promises in Scripture that nature will continue to operate much the same way as it has in the past!
So yes, there is a faith which precedes reason. Many would call this blind faith, but as already correctly pointed out, we ALL must believe in something to start with or we get nowhere. The Christian faith is NOT irrational because it provides the very basis of rationality, while the non-Christian starting point that puts humans as the ultimate standard rather than God gets us nowhere in our thinking!
Christians start with the self-attesting Christ of Scripture and are to interpret all facts under the Lordship of Christ. There is disagreement among people about facts because people who have had their noetic structures affected by sin attempt to interpret facts as something other than what God says that they are. The more we practice our faith the fewer mistakes we make in the realm of thought as our thought becomes more in line with that of God and not of ourselves. There are no new facts to God since He knows all and created all and controls all, thus God gives us infallible information about things as they really are in His Word. God’s Word supplies a starting point for other inferences we may draw without going against Scripture. The senses are generally reliable because they were created by an all powerful God who desires for us to know Him. Knowledge of God comes through knowledge of the world, of Scripture, and of us. God would not have placed any important information that we need in order to know and worship Him outside of our senses. We have a sufficient number and quality of senses to understand the world as God intends. Further, God would not deceive us through making the world something other than what our conceptual maps tell us, for the most part, about the world, since He wants us to come to know Him through His world. We judge our cognitive and sensory tools based upon the objective view of God who stands outside of everything and sees all as it really is, then revealing what He wants to reveal to us.
So yes, we do know things. The non-Christian just does not have any consistent position upon which to stand and know things, whilst the Christian does.