Still it was a good exercise to translate it, and see for myself what it actually says. I concluded that far from being a "charter for free enquiry" as Soma Thera has suggested, it is a more of an apologetic for Buddhist morality. The text basically says this: "if you are an intelligent person, then you will be a good Buddhist". It is aimed at people who are already Buddhist, so it is really saying, "congratulations on choosing Buddhism as your religion, the choice of all right-thinking people". The morality it portrays is attractive however, because it it is located in relationship with other people. We Buddhists can often talk about 'skilful' and 'unskilful' actions in the abstract, but in the Kālāma Sutta it's clear that these terms convey qualities of how we relate people.
In any case the Kālāma Sutta is puzzling in some respects. Although teachers who "proclaim one thing and dispute everything else" are cited, we never quite find out what they teach, nor why they disagree. And although the sutta portrays the ideal Buddhist as dwelling in the brahmavihāras, we are not told how this relates to the morality preceding it. Nor is it clear how the four consolations at the end of the sutta relate to the rest of it.
So it was with interest that I stumbled on the Pāṭaliya Sutta (SN 42.13; PTS S iv.340). Although the setting is different, this is basically the same story as the Kālāma Sutta.  Here the Buddha is in Koliya, rather than Kosala, and the town is called Uttara instead of Kesaputta. The teaching is delivered to a single person, rather than to a group. However the outline of part iii of this sutta is the same as the Kālāma Sutta, and many of the same standard phrases occur in the same places. In the Pāṭaliya various teachers come and teach different things, though this time the teachings are spelled out as various extreme views on the connection between actions and consequences. One can see why their views conflict because they take diametrically opposed stances. However the result is the same: doubt and perplexity. The solution here, though, is to achieve concentration of dhamma and concentration of mind.
One begins by practising the ten right actions.  One who abandons the unskilful states of mind dwells in the brahmavihāra states - mettā, karuṇā, muditā, upekkhā. So here the connection between morality and the brahmavihāras is explicit. Contra later traditions, here one cultivates loving kindness, compassion etc., primarily through practising the precepts, that is primarily through cultivating non-harming (and its corollaries) towards other people. Rather than a seated meditation practice, here the brahmavihāras seem to emerge from personal interactions. From this sublime state of constantly relating to all beings on the basis of kindness and compassion, elsewhere compared to liberation itself, one is able to reflect properly on the content of the various teachings on actions and consequences.
But here's the thing: the text does not untangle the views of these other teachers. It just says that whatever the truth is, the Buddhist is better off (like the Kālāma Sutta this text is a Buddhist apologetic). Whatever the various doctrines are, the virtuous person, dwelling in brahmavihāras, knows that they themselves never oppress anyone and therefore in each case they are "lucky both ways": in this life, and in any future life they are protected by their harmless lifestyle. There is no attempt to engage with the metaphysics of the various doctrines and ideologies. This lack of interest in metaphysics seems to underlie the argument that it doesn't matter what you believe - "Buddhism without beliefs" as it is sometimes called. And maybe it doesn't so long as you relate to all beings with loving kindness and compassion and sympathy. In reality the view that it doesn't matter what you believe is a philosophical fudge. The text is very much in the camp of saying that actions do have consequences, and that we can think of those consequences at the very least as desirable and undesirable, but probably in terms of good and evil as well. And this is a very definite metaphysical position on actions having consequences. Only an naive reading of the Kālāna Sutta concludes that it doesn't matter what you believe, but here in the Pāṭaliya Sutta it is much more clear.
Knowing that they are protected by their own virtue the ideal Buddhist experiences joy, rapture, serenity, bliss and concentration (pamojja, pīti, passadhi, sukha, samādhi) . These are the central steps on the Spiral Path (or upanisās as I call them) and the steps that unite all the textual variations of the Spiral Path. I also see them relating to the jhānas. With joy as a base, I think each item from rapture to samādhi represents the primary quality of a series of increasingly refined states of consciousness roughly equivalent to the first four jhānas.
It is from integration (samādhi) that one is able to dispel perplexity. From a state of equanimous absorption one is able to see things as they are. Though this text leaves the reader at samādhi, dozens of other texts make it clear that it is on the basis of samādhi that knowledge and vision of things as they are (yathābhūta-ñāṇadassana) arises.
The Pāṭaliya Sutta has some advantages over the Kālāma Sutta. Firstly the details of the story are more complete. The kinds of teachings which perplex are spelled out, and it is clear why anyone espousing those views would vehemently disagree with other views. The argument is over whether actions have consequences. Some argue that there are no consequences. One graphic image used for this is going along the banks of the Ganges killing or mutilating every living being. One teacher argues that no evil will result, another that it most certainly will result in evil. Note here that we are not arguing over whether the act itself is evil - we are concerned with consequences. This is a feature of Indian moral philosophy as portrayed in Buddhist texts (whether this is a genuine portrait of Indian moral philosophy is a moot point).
The method of the Buddha is also spelled out, and more clearly linked to the threefold path of morality, meditation & wisdom. Because it incorporates the Spiral Path this is a more coherent telling of the story. The Spiral Path has the special function of showing how liberation is possible. Without it, it is more difficult to see how the unawakened can create the conditions for awakening through living an ethical life, through paying attention in particular ways, and through contemplations leading to seeing through (vipassana). 
This sutta also allows us to see how the four consolations of the ideal Buddhist (ariya-savaka) relate to the views being expressed by the various teachers, and to "being lucky both ways". They aren't stand alone ideas, but link back to the morality under discussion.
This story is told in full no less than three times in the Canon, each time in a different place to a different audience (see note 1). So we should careful about associating it too strongly with the Kālāmas. It's a story, remembered in several different forms. In addition there are cross-over points with some other stories. I think these examples of multiple recensions of stories, with substantial differences, represent different oral lineages. Though I don't have the patience or the skill to do so, I predict that through a detailed examination of the language used in these parallel versions of stories it would be possible to identify lineages of story telling. I gather, for instance, that there are stylistic and even linguistic differences between the various nikāyas - though these might be due to the collators imposing a 'house style' on their collection.
All this goes to show that while making an accurate translation is invaluable, sometimes reading a sutta in context is as important if we are going to understand it fully. And filling out the context can mean painstaking work identifying parallels and related texts. Sometimes the differences between recensions of a story can tell us more than the similarities.
- The Kālāma Sutta (AN 3.65) is repeated more or less verbatim in the next sutta AN 3.66 (A i.190) where it is spoken by the Elder Nandaka to Sāḷha and Rohaṇa; AN 4.193 (A ii.190) contains all of the parts dealing with morality and crossovers with SN 42.13 (S iv.340) which itself spells out the doctrines being disputed (and shows that the consolations are related to them) and that the brahmavihāras are related to the practice of morality; MN 56 (M i.375) shares the SN 42.13 framing story of magical powers for converting other religieux. We should also read the sutta in the light of MN 136 which shows that predicting karmic outcomes is difficult, and MN 60 about alternatives to believing in karma and rebirth.
- i.e. abstention from killing, taking the not given, sexual misconduct, lying, harsh, divisive and idle speech, covetousness, aversion and wrong views - aka the Ten Precepts which are followed by members of the Triratna Order, and by Shingon Buddhists. Sangharakshita has written that: " abstention from killing living beings, or love... is the most direct and most important manifestation of the spiritual and existential act of Going for Refuge. Moreover, it is a principle that finds expression, in one way or another, and to a greater or lesser degree, not only in the First Precept itself, but in all the other Precepts as well." (The Ten Pillars, p.53)
- More than once I have been tempted to suggest that we stop using 'insight' as a translation as the word has other uses in general conversation. Vipassana is from vi- with several senses, but here probably meaning 'through'; and passana 'seen' (a past participle from √paś 'to see'. So in-sight 'to see into' is not accurate in any case! Through-sight would be more accurate. We could replace it with the Greek derived term diaphany, on the model of epiphany. The -phany part comes from the verb phainein "to show"; while dia- means 'across or though' and is very likely cognate with Sanskrit vi- which also ultimately derives from the PIE word for 'two'. So diaphany means 'showing through, or seeing through'. It would be related to diaphanous 'transparent'. The advantage being that we could use insight for it's intended purpose of talking about self knowledge.