One of the ways that critics of inerrancy (the belief that the Bible is entirely true and contains no error of any kind) have sought to undermine the doctrine is by noting the areas where Scripture contradicts itself. These critics hold that because it is clear that genuine contradictions and errors exist in Scripture, then inerrancy—traditionally understood—must be abandoned.
In a recent book on the topic, Peter Enns—a confessing evangelical who no longer holds to inerrancy—examines a particular test case in the book of Acts in order to demonstrate how inerrancy fails to account for obvious discrepancies (read: contradiction) in the biblical text. The problem emerges when one compares two accounts in which Paul describes his conversion experience.
Acts: 9:7: “The men who were traveling with him stood speechless, hearing the voice but seeing no one” (ESV).
Acts 22:9: “Now those who were with me saw the light but did not understand the voice of the one who was speaking to me” (ESV).
The difficulty becomes clear when one notes that the word translated “hearing” in 9:7 is the same word rendered “understand” in 22:9 (akouo). In other words, one text says that the men “heard” the voice (9:7) while the other says the men “did not hear” the voice (22:9). The pressing question: Did the men with the apostle Paul hear or not hear the voice? In Enns’s judgment, when the ESV translates akouo in 22:9 as “to understand,” it does so “out of a perceived need to reconcile the two accounts” (99).
Enns compounds the problem with another observation.
Elsewhere in the New Testament, the verb akouo followed by phone never means simply to understand what was said but to have heard it (and in places to obey, as in John 10:3, 16, 27, 18:37). Of course, hearing implies comprehension, but the expression in the Bible never means “to understand” as distinct from “to hear” and Acts 22:9 is no exception (99).
Generally speaking, Enns believes that inerrantists have a difficult time dealing with textual problems like these, “since [they] challeng[e] the underlying premise that God would be logically consistent and historically accurate” (100). He continues,
To insist here, on (questionable) theological grounds, that one must see these accounts as noncontradictory in order to preserve the nonnegotiable doctrine of inerrancy, despite the words right in front of us, is to tell lay leaders that they cannot trust their own reading skills, and could thereby raise genuine concerns about the intellectual bias of inerrantists” (100-1).
I appreciate Enns call to evangelicals to look squarely into Scripture and to take account of the apparent difficulties. And to the degree that inerrantists are skirting their responsibility to work hard in the text and deal forthrightly with troublesome passages, to that degree we should be admonished. But hard work is just the point, isn’t it?
Inerrancy and Exegetical Excellence
See, as an inerrantist, I am convinced that my theological position on the nature of Scripture and God’s call to exercise the utmost diligence in handling Scripture (1 Tim 2:15) walk the path of hermeneutical practice hand in hand. That is, I believe that tough texts were inspired by God in order to promote exegetical diligence. I believe Scripture is logically consistent and historically accurate, and I experience great spiritual pleasure and joy when I persevere through troubling passages and arrive at reasonable solutions to apparent difficulties. God gave us Acts 9:7 and 22:9 to test our exegetical mettle and give us the opportunity to taste the fruit of persevering discovery.
There may be inerrantists who propose unreasonable solutions due to exegetical laziness, ignorance, or an unwillingness to say, “I don’t know right now.” But the inerrantist position, so far as I can tell, does not necessarily commit one to improbable solutions. How could it? Inerrantists are simply making the claim that Scripture is without error and internally consistent. To say that Scripture is not inerrant based on a textual test case without allowing for a reasonable solution from an inerrantist perspective seems unfair at best and logically fallacious at worst.
In the case of Acts 9:7 and 22:9, I am persuaded that adequate time examining the context, word use, and other factors will provide a reasonable solution to the so-called discrepancy between these two texts.
The Word ‘akouo’ in Luke and Acts
Let’s start with the word akouo. Enns is correct to point out that when the ESV renders akouo as “understand,” it is clearly attempting to relieve the tension between 9:7 and 22:9. If translated literally, it would say in that the men heard (akouo) the voice in 9:7 and later that they did not hear (akouo) the voice. In my judgment, if this is what Luke is saying, then he is making a mistake. The inerrantist position rightly rejects this possibility, but it does not force the interpreter into attempting improbable solutions.
In the case of akouo, I believe it is perfectly legitimate to argue that Luke can use a word with a slightly different sense from one context to the next. Authors do this all the time. In 9:7, Luke indicates that the men heard the voice. That is, they were able to sense auditory vibrations. In 22:9, I believe Luke is speaking, not to the auditory aspect of “hearing,” but to the volitional aspect. Specifically, these men heard the voice but did not hear as to obey. That Luke could be using akouo in this latter sense in 22:9 is supported by the fact that he uses the word like this elsewhere.
What Does it Mean to ‘Hear?’
In several instances in his gospel, Luke reports people hearing something but does not indicate specifically whether or not they responded to what they heard (5:1, 15; 6:18; 15:1). In several cases, the lack of response is not an indication of moral deficiency but simply a feature of the narrative. In other passages, people may hear something and respond to what they heard (1:41, 58, 66; 2:18; 2:20; 47; 4:28; 7:3, 9, 29; 9:7; 14:15; 23:6). Take the centurion for example: “When the centurion heard about Jesus, he sent to him elders of the Jews, asking him to come and heal his servant” (7:3). The centurion’s response to hearing about Jesus was to send out elders.
Yet, many times throughout Luke’s gospel, akouo is used to indicate that one must hear with faith, understanding, and obedience (Luke 6:27, 49; 8:8; 8:10, 12). The implication, then, is that to hear without the response of obedience is to not hear. In the introductory chapters of Acts, Peter’s command to “hear” implies that real hearing will lead to a response of genuine conviction and repentance (Acts 2:22). Peter can judge whether or not the people “heard” his message by their subsequent response or lack thereof.
This usage of akouo throughout the Lukan corpus lays the foundation for how we might understand his use of the word in Acts 9:7 and 22:9. As we turn to chapter 22, we note first that Paul commands his audience to “hear” what he has to say, implying that he wants them to understand his report and believe it (22:1). Then, in his recollection of his Demascus Road experience, he says that he “heard” the voice of the Lord and responded (22:7-8). This “hearing” is contrasted with the “hearing” of those who were with him (22:9). The men heard but did not respond; that is, they did not obey the voice because they did not really “hear” the voice. Auditory vibrations? Yes. The voice of the Lord? No. (It is interesting to note that later in Acts, Paul indicates that he was not disobedient to the heavenly vision but immediately started proclaiming the gospel [26:19].)
Concluding Thoughts
So, while it may appear that the ESV translation of Acts 22:9 may be driven by the theological concern to uphold inerrancy, choosing to translate akouo as “understand” is not entirely without warrant. While I believe one can explain the difference between 9:7 and 22:9 without the aid of the word “understand,” it is clear, given Luke’s use of akouo elsewhere, that “hearing with understanding” is implied in the narrative.
Thus, in the case of the apparent discrepancy between Acts 9:7 and 22:9, it is not necessary that one admit to a formal contradiction in the text of Scripture. Granted, this test case is not the toughest of its kind in the Bible (and Enns admits this later in the book), but it does help illustrate the need for and the reward of pursuing exegetical diligence. Inerrancy, far from enticing interpreters into making forced harmonizations, motivates the interpreter to work hard until the Bible yields its fruit.
From the Study 
Of all the contradictions in the Bible, is this one really worth the effort? What about conflicts in the telling of Resurrection. Admittedly, this is an Islamic perspective, with an apparent agenda, but these conflicts are much more meaningful, IMHO, than Peter’s conversion. http://www.answering-christianity.com/contra_res.htm
As the article states, “That is, I believe that tough texts were inspired by God in order to promote exegetical diligence.” The contractions you pointed to via the link you gave have long had explanations, e.g.:
http://www.answering-islam.org/Andy/Resurrection/harmony.html
This is the advantage of having multiple witnesses. E.g. if you were invited to your neighbour’s 40th party, and you were asked what happened at the party, you’d certainly tell the event a somewhat different way to someone else. Having different accounts is a strength, and diligence is required to piece them together.
With regards to Enn’s, I think the charge is correct; Enn’s doesn’t work hard enough. I reviewed his book, “The Evolution of Adam”. Let me give you one example of this from that review:
“Dr Enns then continues to show how Paul lets his Christology run away with this understanding of Adam. He rightly points out that there are only 3 references in the Old Testament to “Adam”, and two of these refer to geographical locations rather than Adam the first man. This being the case, is Dr Enns right in asserting that the lack of references means Paul is way over-emphasising the significance of Adam?
“Let me conduct a thought experiment. Suppose we give the Old Testament to a group of high school and a group of university students who have never read it. Tell them, too, by all means that Dickens wrote it! Then ask them the question: where did it all go wrong? It would be hard to imagine that they would not immediately point to Adam and Eve and the fall. Within a SINGLE generation you see one brother murder the other. You would have to be callous indeed if this does not make your heart weep. You’d have to be pretty inhuman if you don’t wince with horror at the proud boast of Lamech after he kills a young man for injuring him in Genesis 4:23. So, if the postulation is correct that any sensible college or university student can see with ease the significance of Adam and Eve’s deed, why does Dr Enns think that Paul is overstating the case? Hence, to the question why Adam is so seldom mentioned in the Old Testament; surely one can offer very compelling reasons for this? Immediately after the fall, what do we read in Genesis 4:6, addressed to Cain before he murdered his brother? “Sin is crouching at your door; it desires to have you, but you must rule over it”. The scripture is already unmistakably telling us that each is responsible for his own sin. It is implicitly telling you that, though it is blindingly obvious that Adam is the place where it all went wrong, do not for one moment think that you can diminish your personal responsibility by using Adam as an excuse – hence the lack of references to Adam. The rest of the Old Testament is at pains to reinforce this message again and again. But Paul is surely perfectly right in comparing Adam with Christ. For, until Christ came and paid the penalty for our sins and rose again, it would not have been possible for us to understand that Adam and Christ are firstborns/representatives of two very different and opposing sets of people, with two diametrically opposed outcomes. If Paul hadn’t made this point, someone else would have! What makes perfectly good and reasonable sense seems to be lost in a deluge of contrived conspiracy theories.”